CVE-2021-4120: canonical ltd. snapd Improper Input Validation
Vulnerability summary
CVE-2021-4120 is a high (CVSS 8.2) Improper Input Validation vulnerability in canonical ltd. snapd. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 36.5% of scored vulnerabilities. 2 public exploits are recorded.
Advisory lineage
Upstream 0 · Downstream 3 · Related 3Timeline
- 17-02-2022PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
snapd 2.54.2 fails to perform sufficient validation of snap content interface and layout paths, resulting in the ability for snaps to inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and hence escape strict snap confinement. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HDiffers
- OSV · DebianEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HDiffers
- NVDNIST7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HDiffers
EPSS trend
Probability
0.44%
Chance of exploitation in the next 30 days
Percentile
37%
Versus all other CVEs
30-day change
0.00 pp
From 0.44% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
2 foundExploit Reference (bugs.launchpad.net)
Maturity: unknown
Exploit Reference (openwall.com)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Canonical2 products
- snapd≤ 2.54.2
- ubuntu_linuxEOL18.04 | 20.04 | 21.10
Canonical ltd.1 product
- snapd≥ unspecified, ≤ 2.54.2
Debian1 product
- snapd< 2.54.3-1
Fedoraproject1 product
- fedoraEOL34 | 35
Ubuntu1 product
- snapd< 2.54.3+14.04~esm1 | < 2.54.3+16.04~esm2 | < 2.54.3+18.04 | < 2.54.3+20.04.1
5 vendors · 6 products
References
12 links- www.openwall.com/lists/oss-security/2022/02/18/2Mailing ListX Refsource MLISTExploitThird Party Advisory
