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CVE-2026-81963

HIGH 7.8 KNOWN EXPLOITED ALL-YEARS

Published 2026-09-08 · Last modified 2026-10-14 · microsoft · NVD: Analyzed

Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.

ACTIVELY EXPLOITED

Confirmed exploited in the wild — in CISA KEV since 2026-09-08. Patch or mitigate now.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 33rd percentile

● In CISA KEV (2026-09-08)○ Catalogued PoC◆ SSVC: exploitation active, automatable no

Impact if exploited

7.8CVSS 3.1 · HIGH · CNA

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ⚠Access: Requires local access to the host
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Affected

Vendors Microsoft

Products Windows 11 Version 23h2 Windows 11 Version 24h2 Windows 11 Version 25h2 Windows 11 Version 26h1 Windows Server 2025 Windows Server 2025 (Server Core Installation) Windows 11 23h2 Windows 11 24h2 Windows 11 25h2 Windows 11 26h1

Weakness (CWE)

  • CWE-59: : Improper Link Resolution Before File Access ('Link Following')
  • CWE-284: : Improper Access Control

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

References and research data (JSON)

Unverified PoC candidates

Catalogue matches for further research. These repositories have not been validated as working exploits.

1 candidate

Additional exploitation reports

Source-specific reports, separate from CISA KEV. Repeated observations from one source are not independent confirmations.

  • VulnCheck KEV · 2026-09-08T00:00:00Z

    Source guidance: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

    Source ransomware assessment: Unknown

    VulnCheck KEV · CVE-2026-81963 · Updated 2026-09-08T00:00:00Z
  • VulnCheck KEV · 2026-09-08T00:00:00ZVulnCheck KEV · CVE-2026-81963
    VulnCheck KEV · CVE-2026-81963
    VulnCheck KEV · CVE-2026-81963
    VulnCheck KEV · CVE-2026-81963

Known Affected Software Configurations

VendorProductVersion range
MicrosoftWindows 11 23h2< 10.0.22631.7582
MicrosoftWindows 11 23h2< 10.0.22631.7582
MicrosoftWindows 11 24h2< 10.0.26100.9445
MicrosoftWindows 11 24h2< 10.0.26100.9445
MicrosoftWindows 11 25h2< 10.0.26200.9445
MicrosoftWindows 11 25h2< 10.0.26200.9445
MicrosoftWindows 11 26h1< 10.0.28000.2954
MicrosoftWindows 11 26h1< 10.0.28000.2954
MicrosoftWindows Server 2025< 10.0.26100.33438

All CVSS metrics

  • HIGH 7.8 v3.1 · CNA Primary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
  • HIGH 7.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · All sources and attribution · EPSS