CVE-2025-21311

Windows NTLM V1 Elevation of Privilege Vulnerability

9.8 CriticalFix available

Windows NTLM V1 Elevation of Privilege Vulnerability

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

2.26%Up 2.2 points since Jan 15, 2025

What each source reports

CVE List Score used 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: CVE-2025-21311
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Weakness: CWE-303
Updated: 2026-11-02

EUVDEUVD-2025-2376 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: EUVD-2025-2376
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Updated: 2026-11-02

GitHub AdvisoriesGHSA-29f7-2v24-7hpm 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: GHSA-29f7-2v24-7hpm
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-303
Updated: 2026-11-02

NVD 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: CVE-2025-21311
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-303
Updated: 2026-11-02

OSV 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: CVE-2025-21311
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2025-21311 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: DEBIAN-CVE-2025-21311
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2025-21311 9.8

Windows NTLM V1 Elevation of Privilege Vulnerability

Record: UBUNTU-CVE-2025-21311
CVSS 3.1: 9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`squid` Debian:12	All versions, plus listed versions 5.7-25.7-2+deb12u15.7-2+deb12u25.7-2+deb12u35.7-2+deb12u4 Show 20 moreShow less 5.7-2+deb12u55.7-2+deb12u66.1-16.1-26.10-16.12-16.13-16.13-26.3-16.5-16.6-16.8-16.9-17.1-17.2-17.2-27.4-17.5-17.6-17.6-2	None known
`squid` Debian:13	All versions, plus listed versions 6.13-26.13-2+deb13u16.13-2+deb13u27.1-17.2-1 Show 5 moreShow less 7.2-27.4-17.5-17.6-17.6-2	None known
`squid` Debian:14	before 7.1-1, plus listed versions 6.13-2	7.1-1
`squid3` Ubuntu:Pro:16.04:LTS	All versions, plus listed versions 3.3.8-1ubuntu163.3.8-1ubuntu173.5.12-1ubuntu63.5.12-1ubuntu73.5.12-1ubuntu7.1 Show 22 moreShow less 3.5.12-1ubuntu7.23.5.12-1ubuntu7.33.5.12-1ubuntu7.43.5.12-1ubuntu7.53.5.12-1ubuntu7.63.5.12-1ubuntu7.73.5.12-1ubuntu7.83.5.12-1ubuntu7.93.5.12-1ubuntu7.103.5.12-1ubuntu7.113.5.12-1ubuntu7.123.5.12-1ubuntu7.133.5.12-1ubuntu7.143.5.12-1ubuntu7.153.5.12-1ubuntu7.163.5.12-1ubuntu7.16+esm13.5.12-1ubuntu7.16+esm23.5.12-1ubuntu7.16+esm33.5.12-1ubuntu7.16+esm43.5.12-1ubuntu7.16+esm53.5.12-1ubuntu7.16+esm63.5.12-1ubuntu7.16+esm7	None known
`squid3` Ubuntu:Pro:18.04:LTS	All versions, plus listed versions 3.5.23-5ubuntu13.5.23-5ubuntu23.5.27-1ubuntu13.5.27-1ubuntu1.13.5.27-1ubuntu1.2 Show 18 moreShow less 3.5.27-1ubuntu1.33.5.27-1ubuntu1.43.5.27-1ubuntu1.53.5.27-1ubuntu1.63.5.27-1ubuntu1.73.5.27-1ubuntu1.83.5.27-1ubuntu1.93.5.27-1ubuntu1.103.5.27-1ubuntu1.113.5.27-1ubuntu1.123.5.27-1ubuntu1.133.5.27-1ubuntu1.143.5.27-1ubuntu1.14+esm13.5.27-1ubuntu1.14+esm23.5.27-1ubuntu1.14+esm33.5.27-1ubuntu1.14+esm43.5.27-1ubuntu1.14+esm53.5.27-1ubuntu1.14+esm6	None known
`squid` Ubuntu:Pro:20.04:LTS	All versions, plus listed versions 4.8-1ubuntu24.8-1ubuntu34.9-2ubuntu14.9-2ubuntu24.9-2ubuntu3 Show 18 moreShow less 4.9-2ubuntu44.10-1ubuntu14.10-1ubuntu1.14.10-1ubuntu1.24.10-1ubuntu1.34.10-1ubuntu1.44.10-1ubuntu1.54.10-1ubuntu1.64.10-1ubuntu1.74.10-1ubuntu1.84.10-1ubuntu1.94.10-1ubuntu1.104.10-1ubuntu1.114.10-1ubuntu1.124.10-1ubuntu1.134.10-1ubuntu1.13+esm14.10-1ubuntu1.13+esm24.10-1ubuntu1.13+esm3	None known
`squid` Ubuntu:22.04:LTS	All versions, plus listed versions 4.13-10ubuntu55.2-1ubuntu15.2-1ubuntu35.2-1ubuntu45.2-1ubuntu4.1 Show 13 moreShow less 5.2-1ubuntu4.25.2-1ubuntu4.35.7-0ubuntu0.22.04.15.7-0ubuntu0.22.04.25.7-0ubuntu0.22.04.35.7-0ubuntu0.22.04.45.9-0ubuntu0.22.04.15.9-0ubuntu0.22.04.25.9-0ubuntu0.22.04.35.9-0ubuntu0.22.04.45.9-0ubuntu0.22.04.55.9-0ubuntu0.22.04.75.9-0ubuntu0.22.04.8	None known
`squid` Ubuntu:24.04:LTS	All versions, plus listed versions 6.1-2ubuntu16.1-2ubuntu26.5-1ubuntu16.5-1ubuntu26.5-1ubuntu3 Show 11 moreShow less 6.6-1ubuntu46.6-1ubuntu56.6-1ubuntu5.16.10-0ubuntu0.24.04.16.13-0ubuntu0.24.04.16.13-0ubuntu0.24.04.26.13-0ubuntu0.24.04.36.14-0ubuntu0.24.04.16.14-0ubuntu0.24.04.26.14-0ubuntu0.24.04.46.14-0ubuntu0.24.04.5	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-21311 is a critical vulnerability (CVSS 9.8) in Microsoft Windows 11 Version 24h2, published January 14, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.26%, the 83rd percentile. Fixed in squid 7.1-1.

Attack profile

How easy it is to exploit

What an attacker can affect

Exploit likelihood

What each source reports

Affected products

Affected packages

History

In short

References