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Fencer Vulns
medium 6.1

CVE-2021-20208 json

A flaw was found in cifs-utils in versions before 6.13.

published 2021-04-19 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-7651

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

A flaw was found in cifs-utils in versions before 6.13. A user when mounting a krb5 CIFS file system from within a container can use Kerberos credentials of the host. The highest threat from this vulnerability is to data confidentiality and integrity.

Patch / fix

  • samba cifs-utils 6.13
  • cifs-utils Debian 14, Debian 13, Debian 12 2:6.11-3

debian advisories DEBIAN-CVE-2021-20208

  • cifs-utils Ubuntu 18.04 LTS 2:6.8-1ubuntu1.2
  • cifs-utils Ubuntu 20.04 LTS 2:6.9-1ubuntu0.2
  • cifs-utils Ubuntu Pro 14.04 LTS 2:6.0-1ubuntu2+esm1
  • cifs-utils Ubuntu Pro 16.04 LTS 2:6.4-1ubuntu1.1+esm1

ubuntu advisories UBUNTU-CVE-2021-20208

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • cifs-utils SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 6.9-3.14.1
  • cifs-utils SLE Module for Basesystem 15 SP2 6.9-5.9.1
  • cifs-utils SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 6.9-13.14.1

suse advisories SUSE-SU-2021:1455-1SUSE-SU-2021:1161-1SUSE-SU-2021:1159-1

  • cifs-utils openSUSE Tumbleweed 6.13-1.3
  • cifs-utils openSUSE Leap 15.2 6.9-lp152.2.3.1

opensuse advisories openSUSE-SU-2024:10683-1openSUSE-SU-2021:0639-1

  • cifs-utils Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 6.13-r0

alpine advisories ALPINE-CVE-2021-20208

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • cifs-utils CBL-Mariner 2.0 6.8-6

azure linux advisories AZL-6354

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • cifs-utils Arch Linux 6.13-1

arch linux advisories AVG-1839

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-20208 updated cvss 6.1

cifs-utils: Container can use kerberos cache from the host via mount.cifs/cifs.upcall

  • Red Hat Enterprise Linux 6 cifs-utils Red Hat Enterprise Linux 7 cifs-utils
    affected: workaround, no fix planned “DFS and multiuser mounts can be disabled in the container SMB mounts options i.e. adding 'nodfs' and removing 'multiuser' (if present).”
  • Red Hat Enterprise Linux 8 cifs-utils, pam_cifscreds
    affected: workaround, no fix available “DFS and multiuser mounts can be disabled in the container SMB mounts options i.e. adding 'nodfs' and removing 'multiuser' (if present).”
  • Red Hat Enterprise Linux 6 samba, samba4, samba4-dc, samba-swat, samba4-libs, samba4-pidl, +17 more Red Hat Enterprise Linux 7 ctdb, samba, samba-dc, ctdb-tests, samba-libs, samba-pidl, +18 more Red Hat Enterprise Linux 8 ctdb, samba, libnetapi, ctdb-tests, samba-libs, samba-pidl, +24 more Red Hat Enterprise Linux 9 ctdb, samba, libnetapi, cifs-utils, samba-libs, samba-pidl, +25 more
    not affected: vulnerable code not present “DFS and multiuser mounts can be disabled in the container SMB mounts options i.e. adding 'nodfs' and removing 'multiuser' (if present).”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.67% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:N
NVD 2.0 4.9 AV:N/AC:M/Au:S/C:P/I:P/A:N

Affected products

  • n/a cifs-utils

Classification

Weakness
  • CWE-266 Incorrect Privilege Assignment
  • CWE-269 Improper Privilege Management

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.