CVE-2026-83504

Windows SmartScreen Information Disclosure Vulnerability

CVE-2026-83504 is fixed in 8 products on 1 platform, first by KB5122880, released September 8, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

4.7

Important

Exploitation

None reported

Exploitation Less Likely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0027

19th percentile

<p>Time-of-check time-of-use (toctou) race condition in Windows SmartScreen allows an authorized attacker to disclose information locally.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 11 Version 23H2 for ARM64-based Systems	22631.7582	KB5122880	Sep 8, 2026
Windows 11 Version 23H2 for x64-based Systems	22631.7582	KB5122880	Sep 8, 2026
Windows 11 Version 24H2 for ARM64-based Systems		KB5124008	Sep 8, 2026
Windows 11 Version 24H2 for x64-based Systems		KB5124008	Sep 8, 2026
Windows 11 Version 25H2 for ARM64-based Systems		KB5124008	Sep 8, 2026
Windows 11 Version 25H2 for x64-based Systems		KB5124008	Sep 8, 2026
Windows 11 Version 26H1 for ARM64-based Systems	28000.2954	KB5124012	Sep 8, 2026
Windows 11 version 26H1 for x64-based Systems	28000.2954	KB5124012	Sep 8, 2026

Details

Published
October 13, 2026
Weakness
Time-of-check Time-of-use (TOCTOU) Race Condition
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83504

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