Windows HTTP.sys Elevation of Privilege Vulnerability
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
MSRC compact vulnerability detail
CVE-2026-21240 · Windows HTTP.sys Elevation of Privilege Vulnerability
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
Signals
Windows HTTP.sys
Elevation of Privilege
Exploited: No
Publicly disclosed: No
Exploitability: Exploitation Less Likely
CWE
Patch Diff
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Resolved binary override
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Description
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
FAQ / Articles
FAQ
What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.