CVE-2021-44731Public exploit

Root privilege escalation via symlink-following mount race

Published Feb 17, 2022 · Updated Aug 4, 2024

A race condition in Canonical snapd 2.54.2 allows local users to gain root privileges through a crafted snap mount namespace. setup_private_mount passes an attacker-raced absolute path to mount(), which follows a substituted tmp symlink and bind-mounts attacker-chosen content. Any unprivileged local account can trigger the SUID-root helper; exploitation succeeds on default Ubuntu Desktop and near-default Ubuntu Server installations.

CVSS severity7.8
High
EPSS probability0.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race condition in Canonical snapd 2.54.2 allows local users to gain root privileges through a crafted snap mount namespace. setup_private_mount passes an attacker-raced absolute path to mount(), which follows a substituted tmp symlink and bind-mounts attacker-chosen content. Any unprivileged local account can trigger the SUID-root helper; exploitation succeeds on default Ubuntu Desktop and near-default Ubuntu Server installations.

The record

CVE
CVE-2021-44731
Published
Feb 17, 2022
Updated
Aug 4, 2024
Vendor
Canonical
Product
snapd
Classifications
CWE-362, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 17, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <=2.54.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Canonical · snapdversion=unspecified <=2.54.2

Published CVSS scores

7.8CanonicalCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-362Race Condition (Concurrent Execution using Shared Resource with Improper Synchronization)
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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