CVE-2026-53507 Server-side request forgery in oasdiff-action
Attackers can trigger SSRF and read sensitive files on CI runners via malicious OpenAPI specs in pull requests using oasdiff-action.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-53507?
CVE-2026-53507 is a high-severity server-side request forgery vulnerability in oasdiff-action, published on 31 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-53507?
How do I fix CVE-2026-53507?
No fix has been published for CVE-2026-53507 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-53507 being exploited?
There is no known exploitation of CVE-2026-53507 in the wild and no public exploit code.
Sources
Also known as GHSA-fhj3-7267-7vv5.