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Fencer Vulns
high 7.8

CVE-2021-44731 json

snapd could be made to escalate privileges and run programs as administrator

published 2022-02-17 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-31546

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

A race condition existed in the snapd 2.54.2 snap-confine binary when preparing a private mount namespace for a snap. This could allow a local attacker to gain root privileges by bind-mounting their own contents inside the snap's private mount namespace and causing snap-confine to execute arbitrary code and hence gain privilege escalation. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

Patch / fix

  • snapd Debian 14, Debian 13, Debian 12 2.54.3-1

debian advisories DEBIAN-CVE-2021-44731

  • snapd Ubuntu 18.04 LTS 2.54.3+18.04
  • snapd Ubuntu 20.04 LTS 2.54.3+20.04.1
  • snapd Ubuntu Pro 14.04 LTS 2.54.3+14.04~esm1
  • snapd Ubuntu Pro 16.04 LTS 2.54.3+16.04~esm2

ubuntu advisories UBUNTU-CVE-2021-44731

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

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-2021-44731 updated cvss 7.8

snapd: Race condition in snap-confine's setup_private_mount()

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not 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

0.95% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com http://www.openwall.com/lists/oss-security/2022/02/23/1 referenced PoC, tagged "exploit" by a source, unverified
  • openwall.com http://www.openwall.com/lists/oss-security/2022/11/30/2 referenced PoC, tagged "exploit" by a source, unverified
  • seclists.org http://seclists.org/fulldisclosure/2022/Dec/4 referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Affected products

  • Canonical Ltd. snapd

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

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.