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TI-2021-03546 Aliases CVE-2021-20254GHSA-3r9x-25h6-9v89

Out-of-bounds read in samba

Priority LOW 33CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
High
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Partial Red Hat: 20 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

EPSS 0.01616 76th percentileScored 2026-11-07
Fix Partial Red Hat: 6 advisoriesRed Hat: 20 fixed, 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—sambasamba 4.14.1, samba 4.13.6, samba 4.12.13—No fix listedCNA
  • samba Vendor— Affected samba 4.14.1, samba 4.13.6, samba 4.12.13 Fixed in — No fix listed CNA

CPE configurations NVD · 6

CPEVersionsRoleVendor
cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*3.6.0 to before 4.12.15; 4.13.0 to before 4.13.8; 4.14.0 to before 4.14.4VulnerableSamba
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*32VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*33VulnerableFedoraproject
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*7.0VulnerableRed Hat
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*8.0VulnerableRed Hat
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*9.0VulnerableDebian
  • cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:* Versions 3.6.0 to before 4.12.15; 4.13.0 to before 4.13.8; 4.14.0 to before 4.14.4 Vulnerable ·Samba
  • cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
  • cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Red Hat
  • cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
  • cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian

Remediation

Red Hat 6 advisories

  • RHSA-2021:4866 Released 2021-11-30 · Red Hat rating Moderate
    samba security update
    • Red Hat CodeReady Linux Builder EUS (v. 8.2) libsmbclient-devel-4.11.2-15.el8_2, libwbclient-devel-4.11.2-15.el8_2
    • Red Hat Enterprise Linux BaseOS EUS (v. 8.2) ctdb-4.11.2-15.el8_2, ctdb-tests-4.11.2-15.el8_2, libsmbclient-4.11.2-15.el8_2 +18
  • RHSA-2021:4058 Released 2021-11-02 · Red Hat rating Moderate
    samba security update
    • Red Hat CodeReady Linux Builder (v. 8) libsmbclient-devel-4.13.3-5.el8_4, libwbclient-devel-4.13.3-5.el8_4, samba-devel-4.13.3-5.el8_4
    • Red Hat Enterprise Linux BaseOS (v. 8) ctdb-4.13.3-5.el8_4, ctdb-tests-4.13.3-5.el8_4, libsmbclient-4.13.3-5.el8_4 +19
  • RHSA-2021:3988 Released 2021-10-26 · Red Hat rating Moderate
    samba security update
    • Red Hat Enterprise Linux Server AUS (v. 7.7) libsmbclient-4.9.1-11.el7_7, libwbclient-4.9.1-11.el7_7, samba-4.9.1-11.el7_7 +11
    • Red Hat Enterprise Linux Server E4S (v. 7.7) libsmbclient-4.9.1-11.el7_7, libwbclient-4.9.1-11.el7_7, samba-4.9.1-11.el7_7 +11
    • Red Hat Enterprise Linux Server Optional AUS (v. 7.7) libsmbclient-devel-4.9.1-11.el7_7, libwbclient-devel-4.9.1-11.el7_7, samba-dc-4.9.1-11.el7_7 +8
    • Red Hat Enterprise Linux Server Optional E4S (v. 7.7) libsmbclient-devel-4.9.1-11.el7_7, libwbclient-devel-4.9.1-11.el7_7, samba-dc-4.9.1-11.el7_7 +8
    • Red Hat Enterprise Linux Server Optional TUS (v. 7.7) libsmbclient-devel-4.9.1-11.el7_7, libwbclient-devel-4.9.1-11.el7_7, samba-dc-4.9.1-11.el7_7 +8
    • Red Hat Enterprise Linux Server TUS (v. 7.7) libsmbclient-4.9.1-11.el7_7, libwbclient-4.9.1-11.el7_7, samba-4.9.1-11.el7_7 +11
Show 3 more Red Hat advisories
  • RHSA-2021:3723 Released 2021-10-05 · Red Hat rating Moderate
    samba security, bug fix and enhancement update
    • Red Hat Gluster 3.5 Samba on RHEL-7 ctdb-4.11.6-112.el7rhgs, libsmbclient-4.11.6-112.el7rhgs, libsmbclient-devel-4.11.6-112.el7rhgs +18
  • RHSA-2021:3724 Released 2021-10-05 · Red Hat rating Moderate
    samba security, bug fix and enhancement update
    • Red Hat Gluster 3.5 Samba on RHEL-8 ctdb-4.14.5-201.el8rhgs, libsmbclient-4.14.5-201.el8rhgs, libsmbclient-devel-4.14.5-201.el8rhgs +18
  • RHSA-2021:2313 Released 2021-06-08 · Red Hat rating Moderate
    samba security and bug fix update
    • Red Hat Enterprise Linux Client (v. 7) libsmbclient-4.10.16-15.el7_9, libwbclient-4.10.16-15.el7_9, samba-4.10.16-15.el7_9 +10
    • Red Hat Enterprise Linux Client Optional (v. 7) libsmbclient-devel-4.10.16-15.el7_9, libwbclient-devel-4.10.16-15.el7_9, samba-4.10.16-15.el7_9 +10
    • Red Hat Enterprise Linux ComputeNode Optional (v. 7) libsmbclient-devel-4.10.16-15.el7_9, libwbclient-devel-4.10.16-15.el7_9, samba-4.10.16-15.el7_9 +11
    • Red Hat Enterprise Linux Server (v. 7) libsmbclient-4.10.16-15.el7_9, libsmbclient-4.10.16-15.el7_9.ppc, libwbclient-4.10.16-15.el7_9 +17
    • Red Hat Enterprise Linux Server Optional (v. 7) libsmbclient-devel-4.10.16-15.el7_9, libsmbclient-devel-4.10.16-15.el7_9.ppc, libwbclient-devel-4.10.16-15.el7_9 +14
    • Red Hat Enterprise Linux Server Resilient Storage (v. 7) ctdb-4.10.16-15.el7_9, ctdb-tests-4.10.16-15.el7_9
    • Red Hat Enterprise Linux Workstation (v. 7) libsmbclient-4.10.16-15.el7_9, libwbclient-4.10.16-15.el7_9, samba-4.10.16-15.el7_9 +11
    • Red Hat Enterprise Linux Workstation Optional (v. 7) libsmbclient-devel-4.10.16-15.el7_9, libwbclient-devel-4.10.16-15.el7_9, samba-dc-4.10.16-15.el7_9 +8

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat CodeReady Linux Builder (v. 8)Fixed RHSA-2021:4058
Red Hat CodeReady Linux Builder EUS (v. 8.2)Fixed RHSA-2021:4866
Red Hat Enterprise Linux BaseOS (v. 8)Fixed RHSA-2021:4058
Red Hat Enterprise Linux BaseOS EUS (v. 8.2)Fixed RHSA-2021:4866
Red Hat Enterprise Linux Client (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Client Optional (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux ComputeNode Optional (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Server AUS (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Server E4S (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Server Optional (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Server Optional AUS (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Server Optional E4S (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Server Optional TUS (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Server Resilient Storage (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Server TUS (v. 7.7)Fixed RHSA-2021:3988
Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:2313
Red Hat Enterprise Linux Workstation Optional (v. 7)Fixed RHSA-2021:2313
Red Hat Gluster 3.5 Samba on RHEL-7Fixed RHSA-2021:3723
Red Hat Gluster 3.5 Samba on RHEL-8Fixed RHSA-2021:3724
Not affected: 2 products
  • Red Hat Enterprise Linux 9
  • Red Hat Gluster 3.5 Samba on RHEL-8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-20254
  2. 2026-10-03 Alias added: GHSA-3r9x-25h6-9v89

References

Advisory 7

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences