CVE-2021-39207

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.

Weakness

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Affected Software

Potential Mitigations

• Make fields transient to protect them from deserialization.
• An attempt to serialize and then deserialize a class containing transient fields will result in NULLs where the transient data should be. This is an excellent way to prevent time, environment-based, or sensitive variables from being carried over and used improperly.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/586.html

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