CVE intelligence and bounded remediation

CVE-2021-20254 — A flaw was found in samba

Medium CVSS 6.8

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.

Severity
Medium
CVSS
6.8 (3.1)
Published
2021-05-05
CISA KEV
Not currently listed
Ecosystem
windows/system
Weaknesses
CWE-125

Affected products

  • samba / samba
  • fedoraproject / fedora / 32
  • fedoraproject / fedora / 33
  • redhat / enterprise_linux / 7.0
  • redhat / enterprise_linux / 8.0
  • debian / debian_linux / 9.0

Showing 6 representative product identities from 8 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

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