CVE-2025-21343
High CVSS 7.5Published 2025-01-14 ยท last changed 2026-06-17
The fix
Microsoft fixes this in updatesKB5050021, KB5050009. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Windows 11 Version 22H2 for ARM64-based Systems | 10.0.22621.4751 | KB5050021 | 2026-09-17 |
| Windows 11 Version 22H2 for x64-based Systems | 10.0.22621.4751 | KB5050021 | 2026-09-17 |
| Windows 11 Version 23H2 for ARM64-based Systems | 10.0.22631.4751 | KB5050021 | 2026-09-17 |
| Windows 11 Version 23H2 for x64-based Systems | 10.0.22631.4751 | KB5050021 | 2026-09-17 |
| Windows 11 Version 24H2 for ARM64-based Systems | 10.0.26100.2894 | KB5050009 | 2026-09-17 |
| Windows 11 Version 24H2 for x64-based Systems | 10.0.26100.2894 | KB5050009 | 2026-09-17 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
Windows Web Threat Defense User Service Information Disclosure Vulnerability
Sources
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N