CVE-2021-3155: snapd 2.54.2 and earlier created ~/snap directories in user home directories without specifying owner-only per

Q: How do I fix CVE-2021-3155?

snapd: upgrade to 2.54.3; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-3155 being exploited?

CVE-2021-3155 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-3155 affect?

CVE-2021-3155 affects snapd, ubuntu linux. Severity is low (CVSS 3.8). snapd 2.54.2 and earlier created ~/snap directories in user home directories without specifying owner-only permissions. This could allow a local attacker to read information that should have been private. Fixed in snapd versions 2.54.3+18.0

Q: How urgent is CVE-2021-3155?

Priority 23/100. On your watchlist

Routine

LOW 3.8WATCHLISTUPGRADEMITIGATE

CVE-2021-3155 is a low-severity flaw (CVSS 3.8) affecting snapd, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

snapd 2.54.2 and earlier created ~/snap directories in user home directories without specifying owner-only permissions. This could allow a local attacker to read information that should have been private. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	3.8 (Low)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-276
Published	2022-02-17
Last modified	2026-06-17

Publisher (CNA): Canonical Ltd. · Vendor: canonical

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-02-17 23:15 UTCPublished CVE record published
2026-06-17 04:04 UTCUpdated Record last modified

canonical snapd UPGRADE

Affected: < 2.54.3

Fixed in: 2.54.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy snapd || rpm -q snapd || snapd --version

2. UPGRADE to 2.54.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade snapd

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade snapd

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

canonical ubuntu linux MITIGATE

Affected: 18.04 · 20.04 · 21.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 18.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-3155?

snapd: upgrade to 2.54.3; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-3155 being exploited?

CVE-2021-3155 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-3155 affect?

CVE-2021-3155 affects snapd, ubuntu linux. Severity is low (CVSS 3.8). snapd 2.54.2 and earlier created ~/snap directories in user home directories without specifying owner-only permissions. This could allow a local attacker to read information that should have been private. Fixed in snapd versions 2.54.3+18.0

How urgent is CVE-2021-3155?

Priority 23/100. On your watchlist

Software pages

Ubuntu vulnerabilities

Related CVEs

CVE-2024-5138 HIGH 8.1 UPGRADE The snapctl component within snapd allows a confined snap to interact with the snapd daemon to take certain pr
CVE-2024-29069 MEDIUM 4.8 UPGRADE In snapd versions prior to 2.62, snapd failed to properly check the destination of symbolic links when extract
CVE-2024-29068 MEDIUM 5.8 UPGRADE In snapd versions prior to 2.62, snapd failed to properly check the file type when extracting a snap
CVE-2024-1724 MEDIUM 6.3 UPGRADE In snapd versions prior to 2.62, when using AppArmor for enforcement of sandbox permissions, snapd failed to
CVE-2023-1523 CRITICAL 10.0 UPGRADE MITIGATE Using the TIOCLINUX ioctl request, a malicious snap could inject contents into the input of the controlling te

References

← Back to latest CVEs