Deserialization of Untrusted Data in parlai
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-502.
Summary
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| facebookresearch | ParlAI | before 1.1.0 | 1.1.0 | Patch available | CNA |
| — | parlai (PyPI) | before 1.1.0 | 1.1.0 | Patch available | GHSA-m87f-9fvv-2mgg |
- ParlAI Vendorfacebookresearch Affected before 1.1.0 Fixed in 1.1.0 Patch available CNA
- parlai (PyPI) Vendor— Affected before 1.1.0 Fixed in 1.1.0 Patch available GHSA-m87f-9fvv-2mgg
Remediation
- Fix · CNA ParlAI (facebookresearch) Fixed in 1.1.0
- Fix · GHSA-m87f-9fvv-2mgg parlai (PyPI) Fixed in 1.1.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2021-39207
- 2026-10-03 Alias added: GHSA-m87f-9fvv-2mgg
References
Patch 3
Advisory 2
Other 5
- https://github.com/facebookresearch/ParlAI
- https://github.com/facebookresearch/ParlAI/releases/tag/v1.1.0
- https://github.com/pypa/advisory-database/tree/main/vulns/parlai/PYSEC-2021-330.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/parlai/PYSEC-2021-334.yaml
- http://packetstormsecurity.com/files/164136/Facebook-ParlAI-1.0.0-Code-Execution-Deserialization.html
More facebookresearch vulnerabilities
- TI-2026-48278 Hydra: hydra.utils.instantiate with untrusted config can lead to code execution CVSS 3.1HIGH 7.8
Sources
- CVE-2021-39207 · CVE Program
- CVE-2021-39207 · NVD
- FIRST EPSS
- GHSA-m87f-9fvv-2mgg · GitHub Advisory Database · CC BY 4.0
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