CVE-2026-20929: Microsoft Windows HTTP.sys privilege escalation

CVE-2026-20929 · Severity: high · CVSS 7.5 · Published 2026-01-13

A security vulnerability has been identified in the Windows component responsible for handling web traffic (HTTP.sys). This flaw could allow a user who already has basic access to the network to gain higher-level administrative privileges. If exploited, an attacker could potentially take full control of the affected system, leading to unauthorized data access or service disruption.

Technologies: Microsoft Windows 11, Microsoft Windows 10, Microsoft Windows Server 2008. Vendors: Microsoft.

Quick answers

Is CVE-2026-20929 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-20929 being exploited in the wild.
How severe is CVE-2026-20929?
High severity, with a CVSS score of 7.5, published 13 January 2026.
Which products and versions are affected?
Microsoft Windows 11 Version 22H3, 23H2; Microsoft Windows 10 Version 1607, 1809, 21H2, 22H2; Microsoft Windows Server 2008 Service Pack 2, R2 Service Pack 1.
Is there a fix for CVE-2026-20929?
A patch was published on 2026-01-13. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-20929 attacked?
It is attacked over the network, in an operating system.
Am I affected by CVE-2026-20929?
Check whether you run Microsoft Windows 11, Microsoft Windows 10 or Microsoft Windows Server 2008 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An improper access control vulnerability (CWE-284) exists in the Windows HTTP protocol stack (HTTP.sys). The vulnerability allows an authenticated attacker with low-level privileges to elevate their permissions over the network. Exploitation requires the attacker to have existing network access and authorized credentials, and the attack complexity is rated as high, suggesting specific environmental conditions or timing may be required. Successful exploitation grants the attacker high impact across confidentiality, integrity, and availability. Microsoft has released security updates to address this issue across various versions of Windows and Windows Server.

Affected products

  • Microsoft Windows 10 Version 1607, 1809, 21H2, 22H2
  • Microsoft Windows 11 Version 22H3, 23H2
  • Microsoft Windows Server 2008 Service Pack 2, R2 Service Pack 1

Timeline

  • 2026-01-13: disclosed
  • 2026-01-13: patched

References

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