Is CVE-2025-21311 in the CISA KEV catalog?

No. CVE-2025-21311 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-21311?

CVE-2025-21311 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2025-21311?

CVE-2025-21311 has an EPSS score of 2.17% (80th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-21311?

Upgrade squid on debian unstable to 7.1-1 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2025-21311

CRITICALEPSS 80th pctl

9.8

CVSS v3

NVD

Description

Windows NTLM V1 Elevation of Privilege Vulnerability

CWE-303

How to fix

Remediation Available

squidDebian

Fixed in:7.1-1CVE-2025-21311

Windows 11 Version 24H2Windows

Install:KB5050009Microsoft

Windows Server 2022, 23H2 Edition (Server Core installation)Windows

Install:KB5049984Microsoft

Windows Server 2025Windows

Install:KB5050009Microsoft

Windows Server 2025 (Server Core installation)Windows

Install:KB5050009Microsoft

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

2.17%probability of exploitation in 30 days

80thpercentile

Elevated risk: more likely to be exploited than 80% of all known CVEs.

References

Patch1

msrc.microsoft.com

Related Vulnerabilities

Other CWE-303 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-29357	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-8863	High	8.8	77%	-	-
CVE-2023-32152	Medium	6.5	29%	-	-
CVE-2023-32148	Medium	6.5	27%	-	-
CVE-2022-20695	Critical	10.0	20%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-01-24.