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Vulnerability record · CVE-2026-53507 · published 31 August 2026

CVE-2026-53507: Information exposure vulnerability

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.

8.3 CVSS 4.0 High EPSS 0.50% · top 59.9% CWE-200 · Information exposureCWE-918 · Server-side request forgery (SSRF) Deferred
8.3CVSS 4.0 base score
0.50%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
9 Sep 2026Last modified by NVD

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:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/oasdiff/oasdiff-action/pull/128
https://github.com/oasdiff/oasdiff-action/pull/129
https://github.com/oasdiff/oasdiff-action/pull/130
https://github.com/oasdiff/oasdiff-action/security/advisories/GHSA-fhj3-7267-7vv5

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Source: NIST National Vulnerability Database (record CVE-2026-53507), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.