CVE-2021-20254

MEDIUM
6.8
CVSS Score
Published: May 5, 2021 at 01:36 PM UTC
Updated: June 17, 2026 at 03:33 AM UTC
4 products affected across 4 vendorsDebian LinuxFedoraEnterprise Linux

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Severity
MEDIUM6.8
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.6.0 ≤ v < 4.12.154.13.0 ≤ v < 4.13.84.14.0 ≤ v < 4.14.44.12.134.13.64.14.1
Affected range stops below 4.12.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.13.8, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.14.4, so it looks safe — our inference, not a vendor statement

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-125

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