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CVE-2025-21343: Windows Web Threat Defense User Service Information Disclosure Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-01-14 · updated 2026-06-17
• Weakness: CWE-269

Description

Windows Web Threat Defense User Service Information Disclosure Vulnerability

Affected products

• Microsoft Windows 11: before 10.0.22621.4751 — fixed in 10.0.22621.4751
• Microsoft Windows 11: before 10.0.22631.4751 — fixed in 10.0.22631.4751
• Microsoft Windows 11: before 10.0.26100.2894 — fixed in 10.0.26100.2894
• Microsoft Windows 11: from 10.0.22621.0 before 10.0.22621.4751 — fixed in 10.0.22621.4751
• Microsoft Windows 11 version 22H3: from 10.0.22631.0 before 10.0.22631.4751 — fixed in 10.0.22631.4751
• Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.4751 — fixed in 10.0.22631.4751
• Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.2894 — fixed in 10.0.26100.2894

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.22621.4751; Microsoft Windows 11 10.0.22631.4751; Microsoft Windows 11 10.0.26100.2894; Microsoft Windows 11 10.0.22621.4751; Microsoft Windows 11 version 22H3 10.0.22631.4751; Microsoft Windows 11 10.0.22631.4751; Microsoft Windows 11 10.0.26100.2894. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21343

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