CVE-2026-50420: HTTP.sys Information Disclosure Vulnerability

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-14 · updated 2026-10-28
Weakness: CWE-125

Description

Out-of-bounds read in Windows HTTP.sys allows an unauthorized attacker to disclose information locally.

Affected products

Microsoft Windows 11: before 10.0.26100.8875 — fixed in 10.0.26100.8875
Microsoft Windows 11 25H2: before 10.0.26200.8875 — fixed in 10.0.26200.8875
Microsoft Windows 11 version 26H1: before 10.0.28000.2269; before 10.0.28000.2525 — fixed in 10.0.28000.2269, 10.0.28000.2525
Microsoft Windows Server 2025: before 10.0.26100.33158 — fixed in 10.0.26100.33158
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.8875 — fixed in 10.0.26100.8875
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.8875 — fixed in 10.0.26200.8875
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.2525 — fixed in 10.0.28000.2525
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33158 — fixed in 10.0.26100.33158

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.26100.8875; Microsoft Windows 11 25H2 10.0.26200.8875; Microsoft Windows 11 version 26H1 10.0.28000.2269, 10.0.28000.2525; Microsoft Windows Server 2025 10.0.26100.33158; Microsoft Windows 11 10.0.26100.8875; Microsoft Windows 11 25H2 10.0.26200.8875; Microsoft Windows 11 version 26H1 10.0.28000.2525; Microsoft Windows Server 2025 10.0.26100.33158. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50420

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