CVE-2026-69544: Microsoft Windows 11 version 26H1

Windows SMB Client Elevation of Privilege Vulnerability

CVSS 7.8 HighEPSS 0.0033 · 26th percentile

Published by the CVE Program (CNA: microsoft) at 8 Sept 2026, 17:12 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
Vendor	Product	Versions
Microsoft	Windows 11 version 26H1	affected 10.0.28000.0 to before 10.0.28000.2954 custom

Identifiers

CVE-2026-69544

CNA

microsoft

Weakness (CWE)

CWE-122

Machine-written summary

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

Microsoft Windows 11 version 26H1, builds from 10.0.28000.0 before 10.0.28000.2954, contains a heap-based buffer overflow in the Windows SMB Client. An authorized local attacker can exploit it to elevate privileges. Upgrade to Windows 11 version 26H1 build 10.0.28000.2954 or later. The source gives few details about the attack conditions.

Written 10 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

Score	Rating	CVSS	Vector	Source
7.8	High	3.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C	CNA (microsoft)

CISA KEV Not listed.
EPSS 0.0033, the 26th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

8 Sept 2026, 17:12 UTC Confirmed by the CVE List
31 Oct 2026, 16:20 UTC First seen by agentprime

Sources

References from the CNA

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69544 vendor-advisorypatch

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.