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CVE-2026-97787

7.0 high SSVC exploitation: none Analyzed
NVD · CVE.org

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.

Fix

Microsoft's update · Important

  • KB5126655 — Windows Server 2022, Windows Server 2022 (Server Core installation) · build 10.0.20348.5761 · restart required
  • KB5127646 — Windows 11 Version 26H1, Windows 11 version 26H1 · build 10.0.28000.3231 · restart required
  • KB5126653 — Windows 11 Version 23H2 · build 10.0.22631.7652 · restart required
  • KB5127648 — Windows 11 Version 24H2 · build 10.0.26100.9711 · restart required
  • KB5127648 — Windows 11 Version 25H2 · build 10.0.26200.9711 · restart required
  • KB5127648 — Windows 11 Version 26H2 · build 10.0.26300.9711 · restart required
  • KB5126646 — Windows Server 2025, Windows Server 2025 (Server Core installation) · build 10.0.26100.33650 · restart required

From the 2026-Oct release note of Microsoft's Security Update Guide, revised 2026-11-01 · Exploitation Less Likely.

Patch, vendor advisory and mitigation references on NVD 1

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 3

  1. Cpes+12 CPE criteria (now 12)NVD modified 2026-10-16 10:41
  2. StatusUndergoing Analysis → AnalyzedNVD modified 2026-10-16 10:41
  3. First seenCVSS 7.0NVD modified 2026-10-13 20:19

Affected (CPE criteria) 12

  • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*
  • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*
  • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*
  • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*
  • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*
  • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*
  • cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:arm64:*
  • cpe:2.3:o:microsoft:windows_11_26h1:*:*:*:*:*:*:x64:*
  • cpe:2.3:o:microsoft:windows_11_26h2:*:*:*:*:*:*:arm64:*
  • cpe:2.3:o:microsoft:windows_11_26h2:*:*:*:*:*:*:x64:*
  • cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
  • cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:x64:*

References 1