CVE-2026-53507: CWE-200: Exposure of Sensitive Information to an Unauthorized Actor in oasdiff oasdiff-action
Description
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.
CVSS v4.0
Score 8.3high
Affected software
oasdiff
oasdiff-action
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
oasdiff-action is a GitHub Action that detects breaking changes in OpenAPI specifications. Prior to version 0.0.51, it resolved external $refs by default (allow-external-refs: true). When running on pull requests with attacker-controlled specs, this behavior allowed the action runner to fetch and read arbitrary external references without user interaction, enabling SSRF and potential disclosure of structured files on the runner. This vulnerability is identified as CWE-200 (Exposure of Sensitive Information), CWE-918 (Server-Side Request Forgery), and CWE-1188 (Insecure Default Initialization). The vulnerability has been fixed in version 0.0.51.
Potential Impact
An attacker controlling a pull request OpenAPI spec can cause the action runner to fetch arbitrary external resources, potentially leading to SSRF and unauthorized disclosure of sensitive structured files on the runner. This can compromise confidentiality and integrity of data processed by the runner. No known exploits in the wild have been reported.
Mitigation Recommendations
Upgrade oasdiff-action to version 0.0.51 or later, where the default behavior of resolving external $refs is disabled or properly controlled. This patch prevents automatic fetching of external references in attacker-controlled specs, mitigating SSRF and information disclosure risks.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-09T17:05:25.059Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a95d10facd9273b4979785b
Added to database: 08/31/2026, 19:07:59 UTC
Last enriched: 09/07/2026, 14:52:30 UTC
Last updated: 10/14/2026, 06:48:18 UTC
Views: 80
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