oasdiff actions resolve external $refs by default, enabling SSRF and disclosure of structured files on pull-request runs
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · Low · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-200.
Summary
oasdiff-action is a GitHub Action that detects breaking changes in OpenAPI specs and post a review on every pull request. Before version 0.0.51, the oasdiff actions resolved external $refs in the OpenAPI spec by default (allow-external-refs: true). When an action runs on a pull request whose spec is attacker-controlled — most importantly fork pull requests on public repositories — a $ref in that spec is fetched/read on the runner with no interaction required, enabling SSRF and disclosure of structured files on the runner. This issue has been patched in version 0.0.51.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA oasdiff-action (oasdiff) Fixed in 0.0.51
Timeline
- 2026-10-02 Threatist record created from CVE-2026-53507
References
More oasdiff vulnerabilities
- TI-2026-38582 oasdiff does not enforce --allow-external-refs=false on the git-revision load path (SSRF / local file read) CVSS 4.0MEDIUM 6.0
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences