Microsoft’s October 2026 Patch Tuesday is the year’s largest release, with 1,408 CVEs requiring customer action, 72 of them rated critical. September, the previous high, carried 963. One CVE is already exploited: CVE-2026-96951, a Windows Shell flaw that bypasses Mark of the Web. Two were publicly disclosed before release, in the .NET Framework and the MessagePack-CSharp library. Separately, on 25 September Microsoft reported attacks against CVE-2026-65660, a SharePoint Server flaw fixed in August. Readiness recommends a Patch Now scheduling for Windows, Office, Exchange and the developer tooling, and a standard release schedule for SQL Server. The Readiness team has published an infographic summarising deployment risk by product family.

Known issues

On 14 October, Microsoft added a known issue to this month’s Windows 11 updates, KB5127648 for versions 24H2, 25H2 and 26H2, and KB5127646 for 26H1. Non-admin users might be unable to open Remote Desktop connections to devices that have Administrator protection enabled, with error 0xC000000D. The issue started with September’s non-security preview update. The Windows 11 security baselines enable Administrator protection by default, so test remote access to managed hosts before broad deployment. Microsoft’s mitigation is to turn off Administrator protection temporarily through your policy management tool, and a fix will follow in a future update.

Two issues remain open:

• Some USB Audio Class 1.0 devices might fail to start or produce no sound. The 14 September out-of-band update resolved part of this, and for the remaining symptoms Microsoft directs IT administrators to Microsoft Support for Business.
• Windows Server Update Services still does not display synchronisation error details on Server 2025 and Server 2022. Microsoft removed the function to address CVE-2025-59287 and offers no workaround.

And three are now closed:

• The incorrect “Microsoft Defender Antivirus is turned off” notifications, still open when we published in September, were fixed by Defender Antivirus update 4.18.26080.4, released on 17 September.
• On Windows 11, the October update fixes Explorer failing to start after sign-in on multi-user systems such as Azure Virtual Desktop with FSLogix, which left users at a black screen.
• On Windows 10, Windows 11 23H2 and Server 2016 and 2019, it fixes File History failing to back up or restore and showing a false “Reconnect your drive” message.

Major revisions and mitigations

Between the September and October releases, from 9 September to 12 October, Microsoft’s Security Update Guide notifications covered 111 entries for Microsoft’s own products, not counting Chromium republications for Edge. Of those 111, 90 are true revisions rather than new entries. September’s window had one.

• On 17 September, 84 of September’s CVEs gained Office for Mac updates. Each revision note tells customers running affected Mac software to “install the update for their product to be protected”.
• On 16 September, Microsoft corrected the scoring of three critical SQL Server remote code execution flaws from September, CVE-2026-67378, CVE-2026-67631 and CVE-2026-67643. The scores now record that “an attacker does not require any privileges”. Microsoft calls this an informational change.
• On 25 September, Microsoft revised CVE-2026-65660, a SharePoint Server remote code execution flaw fixed in August, to state that it “had reliable evidence of observed attacks against exploitation of this vulnerability”. CISA added it to its list of known exploited vulnerabilities the same day. The Security Update Guide still shows “Exploited: No” for this CVE, so a report filtered on that flag will miss it. If any SharePoint server lacks the August update, install it now.
• Of the 21 new entries, 18 are critical cloud-side flaws in Azure, Microsoft 365 Copilot, Dataverse and Fabric, all marked “Customer action required: No”. Two are Edge flaws, and one is CVE-2026-96940 in Exchange Server, published on 2 October and covered below.

Microsoft has published no mitigations and no workarounds in the October release.

Windows lifecycle and enforcement updates

These support milestones passed with this release on 13 October, as scheduled:

• Office 2021 retail and Office LTSC 2021, including Skype for Business LTSC 2021, reached the end of support.
• Windows 10 Enterprise 2016 LTSB and Windows 10 IoT Enterprise LTSB 2016 reached the end of extended support.
• Extended Security Updates for Windows Server 2012 and 2012 R2 ended. Year three was the last, so the October update is the final one for both.
• Windows 11 Home and Pro version 24H2 reached the end of updates.
• Windows Server 2022 moved to extended support, which runs to 14 October 2031.

The next milestones fall on 10 November 2026, the date of November’s Patch Tuesday. .NET 8 and .NET 9 reach the end of support, as do PowerShell 7.4 and 7.5. Windows 11 Enterprise and Education 23H2, and IoT Enterprise 23H2, reach the end of updates, and Microsoft says November’s update “will be the last update available for these editions”.

Microsoft also starts or tightens several enforcement changes with this release:

• Windows 11 24H2, 25H2 and 26H2, and Windows Server 2025, now restrict NTLMv1-derived credentials for single sign-on by default. Where Credential Guard is off, Microsoft warns this “might affect Wi-Fi, Ethernet and VPN connections that use MS-CHAPv2-based authentication” (KB5066470).
• AD FS Distributed Key Manager container permissions move into enforcement mode. Supported servers remediate automatically, but Server 2012 and 2012 R2 need manual remediation (KB5121391).
• ReFS volumes on removable media enter an audit phase, and blocking is enabled by default from the January 2027 update (KB5130741).
• The Windows Production PCA 2011 Secure Boot certificate, used to sign the Windows boot loader, expires on 19 October. Devices without its replacement, Windows UEFI CA 2023, keep starting and updating normally, but they stop receiving new early-boot protections (KB5062710).

Microsoft’s test guidance for this release runs to 496 Windows entries, 41 of them flagged as high risk, against 466 and 55 in September. Printing, scanning and font rendering account for 31 of the 41. The Readiness team recommends these testing priorities:

• Printing. Print documents with mixed fonts from 32-bit and 64-bit applications to physical and virtual printers. Add network printers by discovery and by IP address, and print through a shared print server, a USB printer and a PostScript driver.
• Downloaded files. The exploited Shell flaw bypasses Mark of the Web, so open files and shortcuts downloaded from the internet and confirm the SmartScreen and security warnings still appear.
• Remote access. Test Remote Desktop with a non-admin account against hosts that have Administrator protection enabled, and test Wi-Fi and VPN connections that use MS-CHAPv2.
• Application installs. Install, repair and uninstall a representative set of MSI packages, including packages with script custom actions. Windows Installer takes 38 fixes this month.
• Network servers. Run DNS servers (52 fixes) and DHCP servers (18) under load, and confirm leases, zone transfers and conditional forwarders behave as before.

Each month, we break down the update cycle into product families, as defined by Microsoft, with the following groupings.

Browsers

For the third month in a row, Microsoft’s Patch Tuesday release lists no browser CVEs. Edge security fixes arrived between releases instead. Between 9 September and 12 October, Microsoft published 414 CVEs for Microsoft Edge in the Security Update Guide: 409 republished from Chromium and five specific to Edge. None carries an exploited flag, and no Edge release in that period reported an exploit in the wild.

Microsoft Windows

Windows takes 1,122 CVEs this month, 42 of them critical. Elevation of privilege accounts for 617 entries, information disclosure for 200 and remote code execution for 179. Of the 42 critical entries, 31 are remote code execution, nine are elevation of privilege and two are spoofing.

• The exploited flaw is CVE-2026-96951, a Windows Shell security feature bypass that evades Mark of the Web defences. An attacker must convince a user to open a crafted file or follow a link. CISA added it to its list of known exploited vulnerabilities on 13 October, with a remediation date of 16 October.
• DHCP takes 18 fixes, six of them critical remote code execution: five in DHCP Server and one in the DHCP client. DNS Server takes 52, 10 of them remote code execution, though none is critical. Critical remote code execution also affects Hyper-V, Message Queuing, Microsoft QUIC, the Remote Desktop Gateway, Windows Deployment Services, Active Directory Domain Services, NDES and the multicast transport driver.
• In file and image handling, the Raw Image Extension has three critical fixes, one of them a CVE assigned by Cisco Talos, and the PostScript printer driver takes three more. Text shaping takes two, and Media Foundation, the codecs library, the video decoder, GDI+, the graphics component and the Windows PDF component take one each.
• The virtualisation-based security enclave takes eight fixes, five of them critical elevation of privilege.
• The most-patched areas are DNS Server at 52, Win32k at 48, the Windows Kernel at 46 and Windows Installer at 38.

Add this Windows update to your Patch Now schedule. Every client needs the fix for the exploited Shell flaw, and DHCP servers and Hyper-V hosts need the critical server-side fixes.

Microsoft Office

Microsoft released 180 Office CVEs this month, 26 of them critical, and remote code execution accounts for 107.

• Client updates on Windows are Click-to-Run only, for Microsoft 365 Apps, Office LTSC 2021 and Office LTSC 2024. Office for Mac updates ship in the same release this month, rather than nine days later as they did in September. Excel takes 69 fixes, 11 of them critical. Word takes 22, Access 13, Outlook 10 with five critical, PowerPoint nine with four critical, and Visio three, all critical.
• SharePoint Server Subscription Edition takes 34 CVEs in KB5002927, two of them critical. SharePoint Server 2016 and 2019 left extended support on 14 July 2026, and two of this month’s flaws list them as affected with no update: CVE-2026-69943 for both versions and CVE-2026-97783 for 2019.
• Office Online Server takes 43 CVEs in KB5002928. Skype for Business Server takes three, in KB5132779 for 2015 CU13, KB5131693 for 2019 CU8 and KB5131692 for Subscription Edition CU1.

Add these updates to your Patch Now schedule, because 25 of the 26 critical entries affect Excel, Outlook, PowerPoint, Visio and Word.

Microsoft Exchange and SQL Server

Exchange has one critical entry this month and SQL Server has none.

• Exchange Server has seven CVEs across 2016 CU23, 2019 CU14 and CU15, and Subscription Edition: one critical remote code execution, CVE-2026-70571, five elevations of privilege and one spoofing flaw. Six are fixed by the 13 October updates: KB5128895 for Subscription Edition, KB5128896 for 2019 CU15, KB5128897 for 2019 CU14 and KB5128898 for 2016 CU23.
• The seventh, CVE-2026-96940, was published on 2 October. Microsoft lists it against a separate set of updates released that day, KB5129955 to KB5129958, not against the 13 October updates, so confirm both sets are installed. Microsoft rates both CVE-2026-96940 and the critical entry as “Exploitation More Likely”..
• SQL Server has 22 CVEs, none of them critical: eight remote code execution, seven elevation of privilege, four information disclosure and three denials of service. Each supported branch gets a cumulative update and a GDR: 2025 (KB5126967, KB5128492), 2022 (KB5126934, KB5128493), 2019 (KB5128494, KB5128495) and 2017 (KB5128496, KB5128497).

Exchange goes on the Patch Now list. SQL Server goes on the Schedule list because none of its 22 entries is critical. If September’s SQL Server update is still outstanding, install it first.

Microsoft Developer Tools

Microsoft released 66 CVEs across its developer tooling this month: two critical, 63 important and one moderate. Remote code execution accounts for 18 entries and elevation of privilege for 13.

• Both critical entries also affect Windows. CVE-2026-105016 is a remote code execution flaw in Microsoft QUIC that needs no authentication or user interaction, and it affects .NET 8, 9, 10 and 11 on Windows and Visual Studio 2022 and 2026. CVE-2026-96222 is an AD FS certificate validation flaw that Microsoft lists against both the .NET Framework and Windows Server.
• Two entries were publicly disclosed before release. CVE-2026-108398 in the .NET Framework lets an authenticated attacker bypass Windows Defender Application Control. CVE-2026-92707, a denial-of-service vulnerability in the MessagePack-CSharp library assigned by GitHub, affects Visual Studio and the ASP.NET Core SignalR MessagePack protocol.
• Visual Studio Code has 10 fixes, five of them security feature bypasses, and PowerShell 7.4, 7.5 and 7.6 take two.

Add these updates to your Patch Now schedule, starting with the .NET updates that carry the QUIC fix.

Adobe (and third-party updates)

Adobe published 11 security bulletins on 13 October, covering 175 CVEs across ColdFusion, Experience Manager, Commerce, Photoshop, Bridge, FrameMaker, Dimension, the Substance 3D tools and the Content Credentials SDK. None is rated priority 1, and Adobe is not aware of exploits for any of them. No Acrobat or Reader security update for this month. I mentioned last month that we are in for a few months of extraordinary patch releases. Harking back to 2003 (when I started work on the nascent field of Microsoft patch management), with Microsoft releasing just  51 updates, anything over a 1000, much less 1400 CVE entries would have been unimaginable. I don’t think that we are at a “patch maximum” yet — but I hope that things calm down soon.

A chain of vulnerabilities in Google’s Chrome browser could have enabled researchers to take control of one billion Windows machines worldwide — and it cost them just $40,000 in AI compute time to discover it.

Researchers at Xbow USA worked for six days on developing the exploit, which earned them a $250,000 bug bounty from Google, the first under the new 2026 rules.

They chose OpenAI’s GPT-5.6 Sol for the task to demonstrate what’s possible with a publicly available model rather than a specialist security implementation. They used it to search Chrome’s source code, test ideas, and build proofs of concept, while they set the strategy, chose where to look, and checked its work.

They successfully chained together a vulnerability to escape first from the sandbox containing the V8 JavaScript engine and then from Chrome’s operating-system process sandbox, launching a Windows app from within a malicious web page.

Xbow presented its findings to Google, which fixed the flaws. The researchers set out all the details as to how the exploit was developed in a blog.

Microsoft’s September 2026 Patch Tuesday is the year’s largest release, with 963 CVEs requiring customer action, 106 rated critical. Two are already exploited: CVE-2026-81963 in the Windows Update Stack and CVE-2026-85880 in Advanced Local Procedure Call. Nothing in this release was publicly disclosed ahead of the patch. Readiness recommends a Patch Now scheduling for Windows, Office, SQL Server and the developer tooling, and standard patch release for Exchange. The Readiness team has published an infographic summarising deployment risk by product family.

Known issues

Three client issues are carried in from August close with this update, covering:

• Microsoft Teams and the new Outlook failing to launch on ARM devices, such as the Surface Pro 11 and Surface Laptop 7, is resolved by KB5124008. The issue originated in August’s KB5121003 and was most likely on freshly imaged machines that had not yet taken Microsoft Store updates.
• The same update resolved both desktop backgrounds reverting to solid black and mouse cursor customisation resetting on non-English installations. Both originated in the 27 August preview, KB5120998.

And Microsoft has left open a Microsoft Defender Antivirus notification defect, confirmed on 28 August, in which devices report that Defender is turned off while it is running correctly.

Major revisions and mitigations

The quietest revision window of recent months arrived alongside the largest release. Between the August and September Patch Tuesdays, from 12 August to 7 September, the MSRC Security Update Guide touched 324 CVEs. Of those, 307 were routine Microsoft Edge and Chromium republications requiring no customer action.

That leaves 17 entries affecting Microsoft’s own products, and only one of those is a genuine revision. CVE-2026-59133, an elevation of privilege in the High-Performance Computing Pack, moved to version 1.1, and its own revision note records the change as informational. For comparison, August’s window carried 76 revisions to Microsoft’s own products, 60 of them flagged as requiring customer action.

The Readiness team has reviewed all 963 published updates. Microsoft has published no mitigations and no workarounds anywhere in this release.

Windows lifecycle and enforcement updates

Microsoft has published no new service or enforcement deadlines for September. The lifecycle picture is different, with multiple end-of-support notices for this coming October:

• The retail Office 2021 family retires in full, including Access, Excel, Outlook, PowerPoint, Project, Publisher, Visio and Word.
• Office LTSC 2021 reaches end of support, and that includes Skype for Business LTSC 2021.
• Windows 10 2016 LTSB and Windows 10 IoT Enterprise LTSB 2016 reach the end of extended support.
• Windows Server 2012 and 2012 R2 reach the end of Extended Security Update Year 3. This is the final ESU year for both, not a step to a fourth.
• Windows 11 Home and Pro version 24H2 reaches the end of updates.
• Windows Server 2022 moves from mainstream to extended support, where it stays until 14 October 2031.

A second wave follows on 10 November 2026, and it is the one most likely to catch development teams rather than infrastructure teams. .NET 8 reaches the end of its long-term support branch, PowerShell 7.4 does the same, and Windows 11 Enterprise and Education 23H2 ends servicing alongside Windows 11 IoT Enterprise 23H2.

Microsoft’s test guidance for this release runs to 466 Windows entries, 55 of them flagged as high risk, against 109 and four in August. Given the large number of updates this month (who would have thought that we would be here at 963 CVEs), the Readiness team recommends the following testing priorities:

• Printing. Print from 32-bit and 64-bit applications to physical and virtual printers, exercise XPS and PDF output, share a printer from a print server and print from a separate client, cancel a job mid-queue, and confirm the queue reflects every state change. This is 20 of the 55 high risk flags, and it is the single most likely source of a visible regression.
• Fonts, graphics and imaging. Render varied fonts, sizes and styles across browsers, Office, PDF viewers and Notepad, confirm Print Preview matches the printed page, and open JPEG, TIFF, HEIF and raw images across Explorer, Photos and Office. Watch for clipping, distortion and missing glyphs.
• USB Devices. Exercise device attachment and removal. Attach and remove USB audio, video and mass storage devices repeatedly, including through a hub, pair and unpair a wireless device, and confirm each enumerates and releases cleanly. Device Association carries seven high risk flags, and these drivers load whenever hardware is attached.
• Remote Desktop. Open several concurrent sessions, enable printer, clipboard, audio, drive and smart card redirection together, disconnect and reconnect, and confirm redirected devices reattach.
• Storage (ntfs.sys, spaceport.sys). This is a real hotspot for updates this month, but no high-risk changes. Test on hardware you can recover, because the storage changes reach the boot path, potentially resulting in a dead (test) machine.

Each month, we break down the update cycle into product families, as defined by Microsoft, with the following groupings.

Browsers

Microsoft has not released any updates for their browser products for the second month in a row. September’s Security Update Guide carries no Edge-specific CVEs at all, and the 307 Chromium republications in the revision window required no customer action. The nine Edge CVEs that did appear arrived mid-cycle on 28 August and were serviced through the browser’s own update channel rather than this release.

Estates on a managed Edge channel have nothing to do here beyond confirming the channel is current. It is the one quiet corner of an otherwise heavy month.

Microsoft Windows

Windows carries 726 CVEs, 77 of them critical, which is three-quarters of the entire release. Elevation of privilege dominates by volume at 406 entries, with remote code execution second at 156, information disclosure at 94 and denial of service at 47. The pattern is the reverse of the severity picture: the bulk is local elevation, while the critical-rated entries cluster in the network-facing roles.

• Biometrics is a real focus this month as the Windows Biometric Service takes 64 fixes, the largest single-component count of the year. Most of the security issues are heap overflows that give a local attacker SYSTEM. Windows Hello adds nine, all critical. Patch it promptly on any estate using fingerprint or facial sign-in.
• Windows DHCP Server leads at 36 entries and is topped by remote code execution at CVSS 9.8. Windows DNS Server takes 10 more, also reaching 9.8. Critical remote code execution also lands on Message Queuing, RRAS, Services for NFS, the HTTP Print Provider, Windows Shell, Netlogon, Internet Connection Sharing, SSTP and Failover Cluster, all at 9.8. Patch the resolvers, the DHCP servers and the domain controllers first.
• Storage is the heaviest it has been this year. NTFS takes 29 fixes, Spaceport.sys behind Storage Spaces takes 17, and the Overlay Filter takes seven, with the Volume Manager, VHD miniport, iSCSI and Storage Port drivers behind them. These reach the boot path, so stage them on recoverable hardware.
• The rest of the most-patched tally runs Win32k at 19, Microsoft Standard XPS at 18, Windows Error Reporting at 12, and the Windows Kernel, Windows Search, the Print Spooler and the Device Association Service at 11 each.

Add this Windows update to your Patch Now schedule, with DHCP and DNS servers first and the biometric stack close behind.

Microsoft Office

Microsoft released 137 Office CVEs this month, 24 of them critical, with remote code execution the through-line at 69 entries and information disclosure close behind at 52. September breaks the recent pattern in a way that matters for deployment: this wave is not MSI-only.

• Click-to-Run estates are squarely in scope. Roughly 105 of the Office CVEs reach Click-to-Run, so Microsoft 365 Apps, Office 2019, LTSC 2021 and LTSC 2024 all update, on Windows and on Mac. Word takes 35 fixes, Excel 32, PowerPoint 10 and Outlook seven. The heaviest client entries are CVE-2026-78510 in Word and CVE-2026-78509 in Outlook, both critical remote code execution at CVSS 9.8, in document-rendering paths that fire on preview or open.
• SharePoint Server Subscription Edition takes 16 entries and is the only SharePoint baseline with a package this month. Server updates cannot be uninstalled and always require a reboot, so validate in a maintenance window.
• Skype for Business Server takes 10 entries, led by CVE-2026-66302, a critical remote code execution at CVSS 9.8. Patch it and note that the LTSC 2021 edition leaves support on 13 October 2026.

Nothing in Office is exploited this month. With 24 critical-rated entries and the Click-to-Run channel carrying most of the exposure, the September Office updates belong on the Patch Now schedule regardless.

Microsoft Exchange and SQL Server

Exchange is quiet and SQL Server is not, which inverts the usual relationship between the two.

• Exchange Server takes nine CVEs across 2016 CU23, 2019 CU14 and CU15, and Subscription Edition. None is critical and none is exploited, though the highest reaches CVSS 9.3. The mix runs to two remote code execution entries, two elevations of privilege, two spoofing, and one each of tampering, denial of service and information disclosure. Apply the update from an elevated command prompt, because an un-elevated run leaves Exchange services partially patched and broken, then confirm mail flow, Autodiscover and any hybrid connection before returning the server to service.
• SQL Server takes 62 CVEs, four of them critical, across the 2017, 2019, 2022 and 2025 branches. There is no 2016 package this month. Remote code execution leads at 24 entries, with information disclosure at 22. The critical entries are CVE-2026-67631 and CVE-2026-67643 at CVSS 8.8, and CVE-2026-67378 and CVE-2026-67636 at 8.5.
• Eight SQL packages ship, a CU+GDR and an RTM+GDR for each branch: 2025 (KB5122769, KB5122770), 2022 (KB5122768, KB5122771), 2019 (KB5122772, KB5122773) and 2017 (KB5122774, KB5122775). Microsoft’s guidance is explicit that the baseline or RTM version must be installed first and the GDR patch applied on top; test the install and the removal on every servicing branch you run, then restart the service and confirm Always On availability groups stay healthy.

Exchange goes on the Schedule list, and SQL Server goes on the Patch Now list. That is an unusual split, and it is driven by the four critical remote code execution entries on the database estate.

Microsoft Developer Tools

Microsoft released 24 CVEs across its developer tooling this month, 23 rated important and one critical. Security feature bypasses are the main focus with eight CVE entries, with remote code execution and information disclosure at four each.

• The single critical entry is CVE-2026-34182 at CVSS 9.1, a flaw in CMS AuthEnvelopedData processing that allows forged messages to be accepted. It reaches Visual Studio 2017 through 2022.
• The highest-scoring entry in this family is not the critical one. CVE-2026-81376, a Visual Studio Code security feature bypass, reaches CVSS 9.6 while carrying an important rating. It is a useful reminder that severity labels and CVSS scores answer different questions.
• Visual Studio Code and its Copilot extensions take 10 entries, mostly security feature bypasses. Update the editor and confirm workspace trust prompts, extension installation and remote sessions behave as configured.
• .NET ships SDK updates on all three supported lines, x64 and x86: 8.0.131 and 8.0.425, 9.0.121 and 9.0.318, and 10.0.112 and 10.0.401. Install them, then build and run a representative project to check for regressions. Keep the 10 November date for .NET 8 in view while you are in there.
• The .NET Framework ships monthly rollups per operating system: Windows Server 2012 (KB5126147), Server 2012 R2 (KB5126148), Windows 10 1809 (KB5126144), 21H2 (KB5126145), 22H2 (KB5126146) and Server 2022 (KB5126149). One gap worth noting: the 4.7.2 package for Windows 10 1607 is listed as pending and will follow, so estates still on 1607 will not complete their Framework patching this cycle.

Add these to your standard release schedule, behind this month’s Windows, Office and SQL Server priorities. Keep the 10 November date for .NET 8 and PowerShell 7.4 in view while you are in the developer estate, because a patch this month does not extend either branch.

Adobe (and third-party updates)

September is the largest release of the year, and this (crazy, super high) volume is the least interesting thing about it. The 963 CVEs matter less than the 55 entries Microsoft flags as high risk, and those sit in printing and fonts. Adobe shipped two Acrobat builds one digit apart and only the second is a security update (nothing to worry about here). Of the CVEs Microsoft republished, 25 are not Microsoft’s. A version number tells you very little about the work in front of you. So, given my (super-secret knowledge) of how Microsoft operates over the summer, here is my prediction for next month (October). It won’t be as big as this month – but just you wait – November is going to be big. Let’s up those numbers (or not).

The European Union is stepping up its actions against US tech giants under the Digital Markets Act, which is intended to ensure fair competition between digital platforms. On Thursday, the European Commission issued two rulings to limit Google’s dominance.

The Commission ordered Google to open up the Android operating system to AI assistants other than its own Gemini, ensuring that they had the same access to applications and operating system services. A second ruling ordered Google to share search data that only it is big enough to collect with other search engines.

Google has hit back at the measures, warning that they could create security issues for users. “Today’s decisions risk undermining vital privacy and security guardrails for millions of Europeans. We have repeatedly offered solutions to safeguard users while satisfying the DMA’s goals, but these rulings discount extensive evidence of user harm,” said Kent Walker, Google’s President of Global Affairs, in a company blog post.

The EU move doesn’t just cause problems for Google but for CISOs as well, warned Roman Stanek, CEO of Good Data AI. “Enterprise security has always leaned on a simple assumption, that apps are boxes, and the OS decides what crosses the box. But once multiple agents get equal system-level reach, access to screen context, cross-app actions, background execution, that assumption breaks.

“CISOs need to stop treating ‘AI assistant’ as a single, well-understood permission and start treating it as a category risk, one they have to govern like they govern app stores and MDM policies today. That requires device policies that name which agents can hold system-level permissions, not just which apps are installed. It means DLP and conditional access rules that account for an agent reading and acting on data, not just an app requesting it.,” he said.

A vulnerability in GitHub’s browser-based VSCode editor could lead to the theft of a developer’s token under certain circumstances, says a researcher.

The issue, revealed this week in a blog by Ammar Askar, has apparently been already addressed by GitHub owner Microsoft. But it raises a questions about both DevOps security, and about the researcher’s allegation that, because Microsoft doesn’t treat bug discoveries seriously, he can justify giving it short notice before openly publishing vulnerabilities he finds.

First, the bug: Users of github.com may not realize it, but when they are on any repository, they can shift to github.dev and its browser-based version of VSCode just by changing the URL.

Why do this? Because the browser instance of VSCode is pretty powerful, Askar says in his blog. “You can view all the files in the repo (even if it’s a private one), you can send out pull requests, and even make commits.”

Rob Enderle, a IT consultant who heads the Enderle Group, agrees that jumping into VSCode this way is “an incredibly useful tactical tool for quick tasks. By just hitting the ‘.’ key in any GitHub repo, you instantly get a browser-based VS Code interface without having to clone gigabytes of data locally. It’s perfect for rapid PR reviews, quick documentation edits, or navigating code on the fly without breaking your workflow. Just keep in mind that it runs entirely in the browser sandbox; there’s no compute backend, no terminal, and no code execution.”

For any heavy lifting or actual compiling, he added, the developer will still need the raw compute of a local workstation, or a full cloud environment like Codespaces.

The problem, Askar says, is that this functionality is achieved by github.com POSTing over an OAuth token to github.dev that allows it to interact with GitHub on your behalf. “The token is not scoped to the particular repo you interacted with, meaning it has full access to every other repo that you have access to,” he wrote in the blog.

“The presence of this token, and the fact that this web app is running almost the entire brunt of VSCode’s million line Typescript codebase, makes it a great target for anyone looking into VSCode bugs,” he wrote.

The exploit

Askar said that a threat actor could install an extension in a repository using a Jupyter notebook, a web application for creating and sharing computational documents that has the ability to install a malicious local workspace extension while skipping the publisher trust check. In his proof of concept, Askar said that once his payload runs, the newly installed extension will grab the GitHub API token, run a query to get the private repos the developer has access to, and then print out the replies and the token.

This vulnerability also exists in the desktop version of VSCode, Askar said, though it’s harder to exploit, since a threat actor would need to convince the victim to clone their repo and open the notebook containing the webview script payload. “Of course,” he added, “if you [the hacker] had some other XSS [cross-site scripting attack] in a webview that you can get a victim to open, you get effectively full RCE [remote code execution] on their computer.”

In an email, he said this vulnerability was “about as serious as it gets. Any website on the internet could have redirected you to a github.dev link that could have provided an attacker a token to read and modify your code repos. If one could convince the maintainer of a popular software project to click a link, they could have made whatever modifications they wanted to their project.”

This means, said Enderle, “we have to start treating developer endpoints with strict, isolated, zero-trust parameters, because we clearly cannot rely on vendor complacency to protect us.”

This issue reinforces the point that you should never follow any links unless you know exactly where they will take you, added Dwayne McDaniel, principal developer advocate at GitGuardian.

Short notice

Here’s where things get complicated. Because of an unhappy experience when disclosing a previous VSCode vulnerability to Microsoft — the bug was fixed, but Askar wasn’t given credit — this time he only gave GitHub one hour notice that this new discovery was going to be published. Microsoft applied what Askar calls a “stopgap” fix by adding a confirmation when a developer opens notebooks in web VSCode, and by not allowing the trusted publisher requirement to be skipped by commands.

[Related content: When responsible disclosure becomes unpaid labor]

An ethical question

Askar’s short notice raises an ethical question: How far in advance should a responsible researcher give notice to a vendor about a vulnerability before publicly revealing it?

These days, most infosec pros agree that notice must be given, or else a threat actor can quickly exploit a hole. Not only that, but the researcher risks damage to their reputation if reasonable notice isn’t given. Experienced researchers often give vendors at least 30 days to create and distribute a patch.

For their part, vendors often create bug bounty programs, or partner with bug bounty programs, to reward researchers for their work. Unfortunately, some vendors don’t always credit researchers, or downplay the damage a vulnerability can cause. In fact, last month Microsoft and a prominent cybersecurity researcher got into a public spat about one such alleged incident.

An imbalance of power

Asked for comment about Askar’s most recent discovery, a Microsoft spokesperson said, “we value the critical role that the security research community plays in strengthening the security of our products, services, and the broader technology ecosystem. While independent researchers determine when and how to publish their findings, we remain committed to rapidly assessing reported issues, mobilizing the appropriate engineering and security response resources, and delivering mitigations, guidance, and protections as quickly as possible to help safeguard our customers.”

The spokesperson added that the issue Askar reported “has been mitigated for our services and no customer action is required.”

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There is a balance between coordinating disclosure with a software vendor (CVD) and full disclosure, Askar told us. But, he added, there’s an imbalance of power. “A security researcher can pour countless hours into an issue, ensuring they develop a good proof of concept and provide all the steps to recreate the issue. With this, they hope to at least get an acknowledgement for their efforts, which they can use to further their security track record or, in the best case, a monetary bounty reward.”

However, he added, “If security vendors don’t adhere to their side of the bargain, public disclosure is one of the few options security researchers have (if they don’t want to sit on their vulnerabilities or sell them on the black market). It forces the vendor to acknowledge the security issue publicly and usually leads to a much faster resolution than any private communication would.”

This, said Enderle, creates problems for enterprises: “When vendor bureaucracy penalizes responsible disclosure, it alienates the security community and forces public zero-day drops, ultimately leaving enterprise customers holding the bag.”