What’s Vulnerable › Vulnerabilities

CVE-2023-21687: HTTP.sys Information Disclosure Vulnerability

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-02-14 · updated 2026-08-19
• Weakness: CWE-125

Description

HTTP.sys Information Disclosure Vulnerability

Affected products

• Microsoft Windows 11 21H2: before 10.0.22000.1574 — fixed in 10.0.22000.1574
• Microsoft Windows 11: before 10.0.22621.1265 — fixed in 10.0.22621.1265
• Microsoft Windows Server 2022: all versions
• Microsoft Windows 11 21H2: from 10.0.0 before 10.0.22621.1574 — fixed in 10.0.22621.1574
• Microsoft Windows 11: from 10.0.22621.0 before 10.0.22621.1265 — fixed in 10.0.22621.1265
• Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.1547 — fixed in 10.0.20348.1547

How to fix

Upgrade to a fixed version: Microsoft Windows 11 21H2 10.0.22000.1574; Microsoft Windows 11 10.0.22621.1265; Microsoft Windows 11 21H2 10.0.22621.1574; Microsoft Windows 11 10.0.22621.1265; Microsoft Windows Server 2022 10.0.20348.1547. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21687
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21687

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