# CVE-2020-16123: Bypass of snapd pulseaudio restrictions

> A race condition in Ubuntu's PulseAudio allows snaps to bypass confinement restrictions, potentially exposing sensitive information.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Dec 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-h38w-g4mp-rwv7, UBUNTU-CVE-2020-16123, USN-4640-1

## What is CVE-2020-16123?

CVE-2020-16123 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 3 Dec 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

An Ubuntu-specific patch in PulseAudio created a race condition where the snap policy module would fail to identify a client connection from a snap as coming from a snap if SCM_CREDENTIALS were missing, allowing the snap to connect to PulseAudio without proper confinement. This could be exploited by an attacker to expose sensitive information. Fixed in 1:13.99.3-1ubuntu2, 1:13.99.2-1ubuntu2.1, 1:13.99.1-1ubuntu3.8, 1:11.1-1ubuntu7.11, and 1:8.0-0ubuntu3.15.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2020-16123?

It affects 1 product.


Products: Canonical Ubuntu Linux.

## How do I fix CVE-2020-16123?

Apply the vendor's patch.

## Is CVE-2020-16123 being exploited?

There is no known exploitation of CVE-2020-16123 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-16123 and fix it if it is affected.

What it is: CVE-2020-16123 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 3 Dec 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2020-16123 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-16123/ (Markdown: https://insights.sbomify.com/CVE-2020-16123/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-16123
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-16123
- OSV: https://osv.dev/vulnerability/CVE-2020-16123

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-16123/
Summaries are generated and may contain mistakes; the official description above is the record.