What is CVE-2026-85818?

CVE-2026-85818 is a critical-severity vulnerability in Microsoft Windows 11 Version 23h2, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.0/10. Published 2026-10-13.

How severe is CVE-2026-85818?

Critical severity. CVSS v3 base score is 9.0 out of 10.

Vulnerability in Microsoft Windows 11 Version 23h2

CVE-2026-85818

Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to perform spoofing over a network.

Published 2026-10-13 · last modified 2026-10-13.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85818 (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-85818?: CVE-2026-85818 is a critical-severity vulnerability in Microsoft Windows 11 Version 23h2, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.0/10. Published 2026-10-13.
How severe is CVE-2026-85818?: Critical severity. CVSS v3 base score is 9.0 out of 10.