Windows
CVE-2026-21240
HIGH
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
AnalysisAI
Windows HTTP.sys contains a race condition between privilege checks and resource access that enables local authenticated users to escalate privileges on Windows 10 21H2, Windows 11 23H2, and Windows Server 2025. An attacker with valid credentials can exploit this timing vulnerability to gain system-level access. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Local user account with login privileges required. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | CVSS 7.8 (HIGH). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker could exploit this vulnerability to compromise the affected system. |
| Remediation | Monitor vendor advisories for a patch. Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all Windows systems running HTTP.sys and assess user access controls; restrict local administrative privileges and review recent privileged account activity. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
More from same product – last 7 days
Use after free in DigitalCredentials in Google Chrome on Windows prior to 149.0.7827.155 allowed a remote attacker to po
Heap buffer overflow in WebRTC in Google Chrome on Windows prior to 149.0.7827.155 allowed a remote attacker to execute
Use after free in WebShare in Google Chrome on Windows prior to 149.0.7827.155 allowed a remote attacker who had comprom
Use after free in Chromoting in Google Chrome on Windows prior to 149.0.7827.155 allowed a local attacker to perform OS-
Out of bounds read in WebRTC in Google Chrome on Windows prior to 149.0.7827.155 allowed a remote attacker to obtain pot
Share
External POC / Exploit Code
Leaving vuln.today