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Vulnerability record · CVE-2021-39207 · published 10 September 2021

CVE-2021-39207: Facebook parlai deserialization of untrusted data vulnerability

Facebook · Parlai

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.

8.8 CVSS 3.1 High EPSS 1.8% · top 22.5% CWE-502 · Deserialization of untrusted data
8.8CVSS 3.1 base score, v2 6.5
1.8%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Source: NIST National Vulnerability Database (record CVE-2021-39207), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.