# CVE-2020-16126: accountsservice drops ruid, allows unprivileged users to send it signals

> Unprivileged users can send signals to AccountsService due to improper ruid dropping, causing denial of service and potential privilege escalation.

- **Severity:** Low 3.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Nov 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-37qh-6xc5-7fm4, UBUNTU-CVE-2020-16126

## What is CVE-2020-16126?

CVE-2020-16126 is a low-severity vulnerability in Freedesktop accountsservice, published on 11 Nov 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An Ubuntu-specific modification to AccountsService in versions before 0.6.55-0ubuntu13.2, among other earlier versions, improperly dropped the ruid, allowing untrusted users to send signals to AccountService, thus stopping it from handling D-Bus messages in a timely fashion.

Weakness: CWE-269 (Improper Privilege Management)

## Which versions are affected by CVE-2020-16126?

It affects 1 product.


Products: Freedesktop Accountsservice.

## How do I fix CVE-2020-16126?

Apply the vendor's patch.

## Is CVE-2020-16126 being exploited?

There is no known exploitation of CVE-2020-16126 in the wild and no public exploit code.

Public exploit code:

- A bash script exploit of [CVE-2020-16126/CVE-2020-16127] to achieve privilege escalation.Ubuntu 16.04-20.04 LTS本地提权漏洞利用脚本。要求拥有Gnome图形化环境。 (github_poc): https://github.com/zev3n/Ubuntu-Gnome-privilege-escalation

## Other vulnerabilities in Freedesktop accountsservice

- [CVE-2018-14036](https://insights.sbomify.com/CVE-2018-14036/): Path traversal in n/a (medium 6.5)
- [CVE-2020-16127](https://insights.sbomify.com/CVE-2020-16127/): accountsservice .pam_environment infinite loop (low 2.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-16126 and fix it if it is affected.

What it is: CVE-2020-16126 is a low-severity vulnerability in Freedesktop accountsservice, published on 11 Nov 2020. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-16126 in the wild and no public exploit code.

Affected product: Freedesktop accountsservice. 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-2020-16126/ (Markdown: https://insights.sbomify.com/CVE-2020-16126/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-16126
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-16126
- OSV: https://osv.dev/vulnerability/CVE-2020-16126

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-16126/
Summaries are generated and may contain mistakes; the official description above is the record.