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CVE record · CVE-2026-77503

Windows NTFS Elevation of Privilege Vulnerability

CVSS 8.4 HighEPSS 0.0034 · 27th percentile

Published by the CVE Program (CNA: microsoft) at 8 Sept 2026, 17:13 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
Microsoft Windows 10 Version 1607
  • affected 10.0.14393.0 to before 10.0.14393.9512 custom
Microsoft Windows 10 Version 1809
  • affected 10.0.17763.0 to before 10.0.17763.9245 custom
Microsoft Windows 10 Version 21H2
  • affected 10.0.19044.0 to before 10.0.19044.7725 custom
Microsoft Windows 10 Version 22H2
  • affected 10.0.19045.0 to before 10.0.19045.7725 custom
Microsoft Windows 11 version 23H2
  • affected 10.0.22631.0 to before 10.0.22631.7582 custom
Microsoft Windows 11 Version 23H2
  • affected 10.0.22631.0 to before 10.0.22631.7582 custom
Microsoft Windows 11 Version 24H2
  • affected 10.0.26100.0 to before 10.0.26100.9445 custom
Microsoft Windows 11 Version 25H2
  • affected 10.0.26200.0 to before 10.0.26200.9445 custom
Microsoft Windows 11 version 26H1
  • affected 10.0.28000.0 to before 10.0.28000.2954 custom
Microsoft Windows Server 2012
  • affected 6.2.9200.0 to before 6.2.9200.26349 custom
Microsoft Windows Server 2012 (Server Core installation)
  • affected 6.2.9200.0 to before 6.2.9200.26349 custom
Microsoft Windows Server 2012 R2
  • affected 6.3.9600.0 to before 6.3.9600.23398 custom
Microsoft Windows Server 2012 R2 (Server Core installation)
  • affected 6.3.9600.0 to before 6.3.9600.23398 custom
Microsoft Windows Server 2016
  • affected 10.0.14393.0 to before 10.0.14393.9512 custom
Microsoft Windows Server 2016 (Server Core installation)
  • affected 10.0.14393.0 to before 10.0.14393.9512 custom
Microsoft Windows Server 2019
  • affected 10.0.17763.0 to before 10.0.17763.9245 custom
Microsoft Windows Server 2019 (Server Core installation)
  • affected 10.0.17763.0 to before 10.0.17763.9245 custom
Microsoft Windows Server 2022
  • affected 10.0.20348.0 to before 10.0.20348.5622 custom
Microsoft Windows Server 2025
  • affected 10.0.26100.0 to before 10.0.26100.33438 custom
Microsoft Windows Server 2025 (Server Core installation)
  • affected 10.0.26100.0 to before 10.0.26100.33438 custom
Identifiers
CVE-2026-77503
CNA
microsoft
Weakness (CWE)
CWE-125
Tags
Published
8 Sept 2026
Updated
10 Nov 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Windows NTFS in Windows 10, Windows 11 and Windows Server 2012 contains an out-of-bounds read flaw, with affected builds listed for each release. An unauthorized local attacker can exploit it to elevate privileges. Upgrade to the fixed build listed for your Windows version. The source gives few further details.

Written 11 Nov 2026.

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.4 High 3.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C CNA (microsoft)
  • CISA KEV Not listed.
  • EPSS 0.0034, the 27th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 8 Sept 2026, 17:13 UTC Confirmed by the CVE List
  2. 31 Oct 2026, 16:21 UTC First seen by agentprime

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.