What’s Vulnerable › Vulnerabilities

CVE-2021-39207: Deserialization of Untrusted Data in parlai

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-09-10 · updated 2026-06-17
• Weakness: CWE-502

Description

parlai is a framework for training and evaluating AI models on a variety of openly available dialogue datasets. In affected versions the package is vulnerable to YAML deserialization attack caused by unsafe loading which leads to Arbitary code execution. This security bug is patched by avoiding unsafe loader users should update to version above v1.1.0. If upgrading is not possible then users can change the Loader used to SafeLoader as a workaround. See commit 507d066ef432ea27d3e201da08009872a2f37725 for details.

Affected products

• Facebook ParlAI: before 1.1.0 — fixed in 1.1.0

How to fix

Upgrade to a fixed version: Facebook ParlAI 1.1.0. Check the vendor advisory for mitigations.

References

• https://github.com/facebookresearch/ParlAI/commit/4374fa2aba383db6526ab36e939eb1cf8ef99879
• https://github.com/facebookresearch/ParlAI/commit/507d066ef432ea27d3e201da08009872a2f37725
• https://github.com/facebookresearch/ParlAI/security/advisories/GHSA-m87f-9fvv-2mgg
• https://github.com/facebookresearch/ParlAI/commit/4374fa2aba383db6526ab36e939eb1cf8ef99879
• https://github.com/facebookresearch/ParlAI/commit/507d066ef432ea27d3e201da08009872a2f37725
• https://github.com/facebookresearch/ParlAI/security/advisories/GHSA-m87f-9fvv-2mgg

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