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CVE-2021-4120

snapd could be made to bypass intended access restrictions through snap content interfaces and layout paths

Public exploit available. Not confirmed exploited in the wild yet. A vendor fix is available.

CVSS 3.18.2HighEPSS percentile35th0.4% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
Public exploit: 2 sourcesFixVendor fixNo build named by the sources

Published Updated Sources: CVE.org, NVD, BDU

NVD CVE.org

What to do

The vendor has published a fix. Version details are below where the sources state them.

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

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

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS35th
Public exploit
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

2 sources with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

0.4% chance of exploitation activity in the next 30 days, which ranks it in the 35th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 471 days before any public exploit.

  1. OpenVAS check added
  2. Public exploit / PoCsource: other
  3. Patch availablerecord updated
  4. Publishedweakness classified, att&ck mapped

Affected products

And 1 more affected product. See all after sign-in

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Scored 8.2 by NVD.

How it is reached

  • Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction RequiredA user must click a link, open a file, or perform some action

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability HighTotal denial of service — the component is completely unavailable

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 5 more references. See all after sign-in

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