Patch tracker / KB5126836
KB5126836: Windows Server 2012 R2 Security Update (October 2026)
KB5126836 is a Critical security update for Windows Server 2012 R2, released 2026-10-13. It closes 649 CVEs with a maximum CVSS of 9.8. At least one of them is actively exploited (CISA KEV), so it is urgent, and Microsoft lists 1 known issue: test it before broad deployment. The most likely of them to be attacked is CVE-2026-96951, which FIRST.org rates at 10% probability of exploitation in the next 30 days.
Before you deploy: Microsoft lists 1 known issue for this update.
Our data comes from Microsoft, CISA and other public sources, and it can be wrong or out of date. If you are unsure, check the linked source before you act, and tell us when we are wrong so we can fix it.
Update summary
Fixes 649 CVEs. At least one is actively exploited (CISA KEV). Most severe CVSS 9.8 (Critical). EPSS exploit probability up to 9.8%. Among the top half of tracked Microsoft updates by EPSS exploit probability.
Microsoft documents 1 known issue with this update.
- USB audio devices might fail to start or produce no sound
Senserva AI Opinion and rich prompt for KB5126836
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for KB5126836
- Released
- 2026-10-13
- Last changed
- 2026-10-25
- Changes tracked
- 4
Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.
Check if KB5126836 is installed
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Known issues, from Microsoft
Quoted from Microsoft's support article for KB5126836 (checked 2026-11-03). Microsoft lists 1 known issue. Verify against the article before acting.
USB audio devices might fail to start or produce no sound
Symptoms
After installing the September 8, 2026, Windows security update (KB5124012), some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms:
The device displays an error in Device Manager: "This device cannot start (Code 10).”
No audio output.
Volume controls are unresponsive or remain at zero.
Sound settings are unresponsive or unavailable.
Some devices might function in standard stereo configurations but fail when using multichannel audio features, including 8-channel or 3D audio modes. Some customers have reported that they're able to restore audio in these cases by switching to 2-channel mode.
This issue is limited to USB Audio Class 1.0 devices.
Resolution
This issue is partially resolved in the out-of-band (OOB) update released on September 14, 2026, (KB5129243) . This OOB update resolves the symptoms experienced on devices using 8-channel or 3D audio modes. Microsoft is working to address the other symptoms and will provide more information when it is available.
IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.
CVEs fixed by this update
Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.
Scope and sources
- Affected products
- Also released in October 2026
KB5126646
1041 CVEs · Critical · exploitedKB5126651
918 CVEs · Critical · exploitedKB5126653
965 CVEs · Critical · exploitedKB5126655
977 CVEs · Critical · exploitedKB5126657
899 CVEs · Critical · exploitedKB5126868
769 CVEs · Critical · exploitedKB5127646
997 CVEs · Critical · exploitedKB5127648
1009 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.