Security readout for executives and security teams
Plain-English summary
ParlAI versions before 1.1.0 can unsafe-load YAML data, allowing arbitrary code execution in affected use. This matters most where ParlAI processes YAML configuration or data from users, pipelines, or shared repositories. The vendor fixed the issue by avoiding unsafe YAML loading.
Executive priority
Treat as a high-priority dependency remediation where ParlAI is used in model training, evaluation, or automation. The business risk is code execution in ML tooling, especially if YAML files cross trust boundaries.
Technical view
CVE-2021-39207 is CWE-502 in facebookresearch ParlAI before 1.1.0. Unsafe YAML deserialization could execute attacker-controlled objects. CVSS 3.1 is 8.4, with network attack vector, high complexity, low privileges, no user interaction, changed scope, and high confidentiality and integrity impact.
Likely exposure
Exposure is likely limited to systems using ParlAI versions below 1.1.0 that load YAML content influenced by users, jobs, datasets, or automation. Organizations not using ParlAI, or using newer fixed releases, are not indicated as affected by the provided sources.
Exploitation context
The source bundle does not show CISA KEV listing or confirmed active exploitation. The advisory describes potential arbitrary code execution through unsafe YAML loading. Exploitation appears constrained by high attack complexity and low privileges according to the CVSS vector.
Researcher notes
The provided sources identify the vulnerability class, affected versions, CVSS vector, and remediation direction. They do not provide evidence of active exploitation. Focus validation on unsafe YAML loading paths and whether local deployments permit untrusted YAML influence.
Mitigation direction
- Upgrade ParlAI to a version above v1.1.0.
- If upgrading is not possible, change YAML loading to use SafeLoader.
- Review vendor advisory and linked commits for implementation details.
- Restrict untrusted YAML inputs until fixed versions are deployed.
Validation and detection
- Inventory Python environments and containers for facebookresearch ParlAI usage.
- Confirm installed ParlAI versions are not below 1.1.0.
- Review code paths that load YAML in ParlAI-based workflows.
- Check whether YAML inputs come from users, datasets, CI, or shared repositories.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-502: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-39207 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L1.86Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.4HighVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/facebookresearch/ParlAI/security/advisories/GHSA-m87f-9fvv-2mggCVE reference · x_refsource_CONFIRM
- https://github.com/facebookresearch/ParlAI/commit/4374fa2aba383db6526ab36e939eb1cf8ef99879CVE reference · x_refsource_MISC
- https://github.com/facebookresearch/ParlAI/commit/507d066ef432ea27d3e201da08009872a2f37725CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Deserialization of Untrusted Data
Deserialization of Untrusted Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.