CVE-2025-53805: HTTP.sys Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-09 · updated 2026-06-17
Weakness: CWE-125

Description

Out-of-bounds read in Windows Internet Information Services allows an unauthorized attacker to deny service over a network.

Affected products

Microsoft Windows 11: before 10.0.22621.5909 — fixed in 10.0.22621.5909
Microsoft Windows 11: before 10.0.22631.5909 — fixed in 10.0.22631.5909
Microsoft Windows 11: before 10.0.26100.6508 — fixed in 10.0.26100.6508
Microsoft Windows Server 2022: before 10.0.20348.4106 — fixed in 10.0.20348.4106
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1849 — fixed in 10.0.25398.1849
Microsoft Windows Server 2025: before 10.0.26100.6508 — fixed in 10.0.26100.6508
Microsoft Windows 11: from 10.0.22621.0 before 10.0.22621.5909 — fixed in 10.0.22621.5909
Microsoft Windows 11 version 22H3: from 10.0.22631.0 before 10.0.22631.5909 — fixed in 10.0.22631.5909
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.5909 — fixed in 10.0.22631.5909
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.6584 — fixed in 10.0.26100.6584
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.4171 — fixed in 10.0.20348.4171
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.1849 — fixed in 10.0.25398.1849
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.6584 — fixed in 10.0.26100.6584

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.22621.5909; Microsoft Windows 11 10.0.22631.5909; Microsoft Windows 11 10.0.26100.6508; Microsoft Windows Server 2022 10.0.20348.4106; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1849; Microsoft Windows Server 2025 10.0.26100.6508; Microsoft Windows 11 10.0.22621.5909; Microsoft Windows 11 version 22H3 10.0.22631.5909; Microsoft Windows 11 10.0.22631.5909; Microsoft Windows 11 10.0.26100.6584; Microsoft Windows Server 2022 10.0.20348.4171; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1849. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53805

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