Security readout for executives and security teams
Plain-English summary
On Ubuntu, a Snap app with audio permissions could bypass intended PulseAudio access restrictions by unloading Ubuntu’s Snap policy module. This is a local, low-severity issue with limited confidentiality impact in the published CVSS assessment.
Executive priority
Treat as routine patching for Ubuntu desktops and snap-enabled endpoints. It is not a network remote compromise, but it weakens Snap audio access boundaries and should be closed during normal security maintenance.
Technical view
Ubuntu’s PulseAudio packages included Snap mediation code. For snaps plugging pulseaudio, audio-playback, or audio-record, the policy module could be unloaded, bypassing intended access controls. Affected package streams are 1:8.0, 1:11.1, 1:13.0, and 1:13.99.1 before the Ubuntu fixed versions.
Likely exposure
Exposure is mainly Ubuntu systems running affected PulseAudio packages and Snap-packaged applications using PulseAudio-related interfaces. Server exposure is likely limited unless desktop audio and snaps are present.
Exploitation context
The CVSS vector is local, low complexity, low privileges, no user interaction, unchanged scope, and low confidentiality impact. The bundle does not cite active exploitation, and KEV status is false.
Researcher notes
This is Ubuntu-specific and tied to Canonical’s PulseAudio Snap mediation changes, not a general upstream PulseAudio vulnerability. Evidence supports a policy bypass by module unloading; it does not support claims of broader privilege escalation or active exploitation.
Mitigation direction
- Apply Ubuntu security updates from USN-4355-1.
- Upgrade PulseAudio to the fixed version for the installed Ubuntu release.
- Prioritize snap-enabled workstations using audio playback or recording snaps.
- Check Canonical guidance for any release-specific remediation details.
Validation and detection
- Inventory Ubuntu hosts with PulseAudio and Snap installed.
- Verify installed PulseAudio versions are at or above Ubuntu’s fixed package versions.
- Review snap applications using pulseaudio, audio-playback, or audio-record interfaces.
- Confirm security update records show USN-4355-1 applied where relevant.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-284: Authorization and privilege behavior lookup
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Open ATT&CK lookupCVE-2020-11931 mapping review
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Open ATT&CK lookup- Severity
- Low
- CVSS
- 3.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N1.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
3.3LowVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://forum.snapcraft.io/t/audio-switcher-pulseaudio-interface-auto-connect-request/16648/3CVE reference · x_refsource_MISC
- USN-4355-1CVE reference · vendor-advisory, x_refsource_UBUNTU
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Access Control
Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.