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TI-2026-17149 Aliases CVE-2026-21240GHSA-56fh-gxc8-3p64

Windows HTTP.sys Elevation of Privilege Vulnerability

Priority LOW 36CWE-367Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Privilege escalation
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Microsoft. Impact type from Microsoft.

Summary

Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00276 20th percentileScored 2026-11-07
Fix Fixed Microsoft: 11 updates

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftWindows 10 Version 180910.0.17763.0 to before 10.0.17763.838910.0.17763.8389Patch availableCNA
MicrosoftWindows 10 Version 21H210.0.19044.0 to before 10.0.19044.693710.0.19044.6937Patch availableCNA
MicrosoftWindows 10 Version 22H210.0.19045.0 to before 10.0.19045.693710.0.19045.6937Patch availableCNA
MicrosoftWindows 11 version 22H310.0.22631.0 to before 10.0.22631.664910.0.22631.6649Patch availableCNA
MicrosoftWindows 11 Version 23H210.0.22631.0 to before 10.0.22631.664910.0.22631.6649Patch availableCNA
MicrosoftWindows 11 Version 24H210.0.26100.0 to before 10.0.26100.784010.0.26100.7840Patch availableCNA
MicrosoftWindows 11 Version 25H210.0.26200.0 to before 10.0.26200.784010.0.26200.7840Patch availableCNA
MicrosoftWindows 11 version 26H110.0.28000.0 to before 10.0.28000.157510.0.28000.1575Patch availableCNA
MicrosoftWindows 11 Version 26H110.0.28000.0 to before 10.0.28000.157510.0.28000.1575Patch availableCNA
MicrosoftWindows Server 201910.0.17763.0 to before 10.0.17763.838910.0.17763.8389Patch availableCNA
MicrosoftWindows Server 2019 (Server Core installation)10.0.17763.0 to before 10.0.17763.838910.0.17763.8389Patch availableCNA
MicrosoftWindows Server 202210.0.20348.0 to before 10.0.20348.477310.0.20348.4773Patch availableCNA
MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)10.0.25398.0 to before 10.0.25398.214910.0.25398.2149Patch availableCNA
MicrosoftWindows Server 202510.0.26100.0 to before 10.0.26100.3237010.0.26100.32370Patch availableCNA
MicrosoftWindows Server 2025 (Server Core installation)10.0.26100.0 to before 10.0.26100.3237010.0.26100.32370Patch availableCNA
  • Windows 10 Version 1809 VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.8389 Fixed in 10.0.17763.8389 Patch available CNA
  • Windows 10 Version 21H2 VendorMicrosoft Affected 10.0.19044.0 to before 10.0.19044.6937 Fixed in 10.0.19044.6937 Patch available CNA
  • Windows 10 Version 22H2 VendorMicrosoft Affected 10.0.19045.0 to before 10.0.19045.6937 Fixed in 10.0.19045.6937 Patch available CNA
  • Windows 11 version 22H3 VendorMicrosoft Affected 10.0.22631.0 to before 10.0.22631.6649 Fixed in 10.0.22631.6649 Patch available CNA
  • Windows 11 Version 23H2 VendorMicrosoft Affected 10.0.22631.0 to before 10.0.22631.6649 Fixed in 10.0.22631.6649 Patch available CNA
  • Windows 11 Version 24H2 VendorMicrosoft Affected 10.0.26100.0 to before 10.0.26100.7840 Fixed in 10.0.26100.7840 Patch available CNA
  • Windows 11 Version 25H2 VendorMicrosoft Affected 10.0.26200.0 to before 10.0.26200.7840 Fixed in 10.0.26200.7840 Patch available CNA
  • Windows 11 version 26H1 VendorMicrosoft Affected 10.0.28000.0 to before 10.0.28000.1575 Fixed in 10.0.28000.1575 Patch available CNA
  • Windows 11 Version 26H1 VendorMicrosoft Affected 10.0.28000.0 to before 10.0.28000.1575 Fixed in 10.0.28000.1575 Patch available CNA
  • Windows Server 2019 VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.8389 Fixed in 10.0.17763.8389 Patch available CNA
  • Windows Server 2019 (Server Core installation) VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.8389 Fixed in 10.0.17763.8389 Patch available CNA
  • Windows Server 2022 VendorMicrosoft Affected 10.0.20348.0 to before 10.0.20348.4773 Fixed in 10.0.20348.4773 Patch available CNA
  • Windows Server 2022, 23H2 Edition (Server Core installation) VendorMicrosoft Affected 10.0.25398.0 to before 10.0.25398.2149 Fixed in 10.0.25398.2149 Patch available CNA
  • Windows Server 2025 VendorMicrosoft Affected 10.0.26100.0 to before 10.0.26100.32370 Fixed in 10.0.26100.32370 Patch available CNA
  • Windows Server 2025 (Server Core installation) VendorMicrosoft Affected 10.0.26100.0 to before 10.0.26100.32370 Fixed in 10.0.26100.32370 Patch available CNA

CPE configurations NVD · 18

CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*before 10.0.17763.8389VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*before 10.0.17763.8389VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*before 10.0.19044.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*before 10.0.19044.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*before 10.0.19044.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*before 10.0.19045.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:*before 10.0.19045.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:*before 10.0.19045.6937VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*before 10.0.22631.6649VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*before 10.0.22631.6649VulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:* Versions before 10.0.17763.8389 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:* Versions before 10.0.17763.8389 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:* Versions before 10.0.19044.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:* Versions before 10.0.19044.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:* Versions before 10.0.19044.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:* Versions before 10.0.19045.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:* Versions before 10.0.19045.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:* Versions before 10.0.19045.6937 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:* Versions before 10.0.22631.6649 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:* Versions before 10.0.22631.6649 Vulnerable ·Microsoft
Show 8 more CPE
CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*before 10.0.26100.7781VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*before 10.0.26100.7781VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*before 10.0.26200.7781VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*before 10.0.26200.7781VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*before 10.0.17763.8389VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*before 10.0.20348.4711VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*before 10.0.25398.2149VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*before 10.0.26100.32313VulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:* Versions before 10.0.26100.7781 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:* Versions before 10.0.26100.7781 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:* Versions before 10.0.26200.7781 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:* Versions before 10.0.26200.7781 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* Versions before 10.0.17763.8389 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:* Versions before 10.0.20348.4711 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:* Versions before 10.0.25398.2149 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:* Versions before 10.0.26100.32313 Vulnerable ·Microsoft

Remediation

Microsoft 11 updates

  • KB5077212
    Security Hotpatch Update
    • Windows 11 Version 24H2 for ARM64-based Systems 10.0.26100.7781
    • Windows 11 Version 24H2 for x64-based Systems 10.0.26100.7781
    • Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.7781
    • Windows 11 Version 25H2 for x64-based Systems 10.0.26200.7781
  • KB5077181
    Security Update
    • Windows 11 Version 24H2 for ARM64-based Systems 10.0.26100.7840
    • Windows 11 Version 24H2 for x64-based Systems 10.0.26100.7840
    • Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.7840
    • Windows 11 Version 25H2 for x64-based Systems 10.0.26200.7840
  • KB5077179
    Security Update
    • Windows 11 Version 26H1 for ARM64-based Systems 10.0.28000.1575
    • Windows 11 version 26H1 for x64-based Systems 10.0.28000.1575
Show 8 more Microsoft updates
  • KB5075943
    Security Hotpatch Update
    • Windows Server 2022 10.0.20348.4711
    • Windows Server 2022 (Server Core installation) 10.0.20348.4711
  • KB5075942
    Security Hotpatch Update
    • Windows Server 2025 10.0.26100.32313
    • Windows Server 2025 (Server Core installation) 10.0.26100.32313
  • KB5075941
    Security Update
    • Windows 11 Version 23H2 for ARM64-based Systems 10.0.22631.6649
    • Windows 11 Version 23H2 for x64-based Systems 10.0.22631.6649
  • KB5075912
    Security Update
    • Windows 10 Version 21H2 for 32-bit Systems 10.0.19044.6937
    • Windows 10 Version 21H2 for ARM64-based Systems 10.0.19044.6937
    • Windows 10 Version 21H2 for x64-based Systems 10.0.19044.6937
    • Windows 10 Version 22H2 for 32-bit Systems 10.0.19045.6937
    • Windows 10 Version 22H2 for ARM64-based Systems 10.0.19045.6937
    • Windows 10 Version 22H2 for x64-based Systems 10.0.19045.6937
  • KB5075906
    Security Update
    • Windows Server 2022 10.0.20348.4773
    • Windows Server 2022 (Server Core installation) 10.0.20348.4773
  • KB5075904
    Security Update
    • Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8389
    • Windows 10 Version 1809 for x64-based Systems 10.0.17763.8389
    • Windows Server 2019 10.0.17763.8389
    • Windows Server 2019 (Server Core installation) 10.0.17763.8389
  • KB5075899
    Security Update
    • Windows Server 2025 10.0.26100.32370
    • Windows Server 2025 (Server Core installation) 10.0.26100.32370
  • KB5075897
    Security Update
    • Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2149

Vendor assessments

Microsoft

Microsoft's page for this CVE →

Impact
Elevation of Privilege
Exploited
No
Publicly disclosed
No
Exploitability
Exploitation Less Likely

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-21240
  2. 2026-10-03 Alias added: GHSA-56fh-gxc8-3p64

References

Patch 1

  • TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-73128 Windows Shell Security Feature Bypass Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2026-17367 MSHTML Framework Security Feature Bypass Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2026-17364 Windows Shell Security Feature Bypass Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2025-24062 Windows SMB Client Elevation of Privilege Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2025-24042 Internet Shortcut Files Remote Code Execution Vulnerability KEVCVSS 3.1HIGH 8.8
See all 4016 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences