Is CVE-2021-20254 in the CISA KEV catalog?

No. CVE-2021-20254 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-20254?

CVE-2021-20254 has a CVSS v3 base score of 6.8 (MEDIUM).

What is the EPSS score for CVE-2021-20254?

CVE-2021-20254 has an EPSS score of 1.62% (73th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-20254?

Upgrade samba on debian 11 to 2:4.13.5+dfsg-2 or later. Fixes are available for 2 affected products.

CVE & CISA-KEV Catalog

CVE-2021-20254

MEDIUMEPSS 73th pctl

6.8

CVSS v3

NVD

Description

A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity.

CWE-125Out-of-bounds Read

How to fix

Remediation Available

sambaDebian

Fixed in:2:4.13.5+dfsg-2CVE-2021-20254

sambaUbuntu

Fixed in:2:4.3.11+dfsg-0ubuntu0.14.04.20+esm11USN-4931-1

Fixed in:2:4.3.11+dfsg-0ubuntu0.16.04.34USN-4930-1

Fixed in:2:4.7.6+dfsg~ubuntu-0ubuntu2.23USN-4930-1

Fixed in:2:4.11.6+dfsg-0ubuntu1.8USN-4930-1

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 ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

1.62%probability of exploitation in 30 days

73rdpercentile

Elevated risk: more likely to be exploited than 73% of all known CVEs.

References

Vendor Advisory1

samba.org

Third-Party Advisory4

Other references2

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0160	High	7.5	100%	KEV	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2021-4034	High	7.8	95%	KEV	Fix
CVE-2023-21769	High	7.5	92%	-	Fix
CVE-2023-49285	High	8.6	89%	-	Fix
CVE-2020-8794	Critical	9.8	89%	-	Fix

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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 2024-11-21.