VulnerabilityDeferred

CVE-2026-53507

Before version 0.0.51, the oasdiff actions resolved external $refs in the OpenAPI spec by default (allow-external-refs: true).

HIGH 8.3EPSS 0.29%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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: 8.3 HIGHCVSS: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/M
EPSS: 0.29% probability · 21th percentile
CISA KEV: Not listed
Weakness: CWE-200, CWE-918, CWE-1188
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.