{"id":"GHSA-2jcc-mxv7-p3f9","summary":"oasdiff does not enforce --allow-external-refs=false on the git-revision load path (SSRF / local file read)","details":"## Summary\n\nFrom **v1.13.2** through **v1.18.0**, oasdiff did not enforce `--allow-external-refs=false` (library: `openapi3.Loader.IsExternalRefsAllowed = false`) when loading a spec from a **git revision** (the `rev:path` form, e.g. `main:openapi.yaml`). External `$ref`s were resolved on that load path even when external refs were explicitly disabled, so the mitigation silently did not apply there.\n\n## Impact\n\nA caller who set `--allow-external-refs=false` *specifically to safely process untrusted specs* remained exposed — on the git-revision load path only — to:\n\n- **SSRF** via `$ref: \"http://\u003cinternal-host\u003e/…\"`, and\n- **Local file reads** via `$ref: \"/path\"` or `file://`.\n\nAffected callers:\n\n- **CLI:** `oasdiff diff main:openapi.yaml HEAD:openapi.yaml --allow-external-refs=false` (and `breaking` / `changelog` / `summary`, and the `git-diff-driver`) run over untrusted spec content.\n- **Go library consumers** of `github.com/oasdiff/oasdiff/load` that set `IsExternalRefsAllowed = false` and load from a git-revision source via `load.NewSpecInfo`.\n\nThe file and URL load paths correctly enforced the setting; only the git-revision path was affected. Callers that left external refs at the default (`true`) are not in scope for *this* advisory.\n\n## Patches\n\n**v1.18.1** enforces the external-refs policy on the git-revision path (so `--allow-external-refs=false` now blocks external `$ref`s there) and returns a dedicated exit code (`123`) when an external `$ref` is refused.\n\n## Workarounds\n\n- Upgrade to **v1.18.1**, or\n- Avoid the git-revision input form when processing untrusted specs with external refs disabled.\n\n## Notes\n\n- Introduced in **v1.13.2** (#832, which added `$ref`-chain resolution on the git-revision path); fixed in **v1.18.1** (#974, #975).\n- The permissive **default** (`allow-external-refs: true`) and its zero-interaction exposure in CI via the GitHub Action is tracked separately in GHSA-fhj3-7267-7vv5 (oasdiff-action).","aliases":["CVE-2026-53508","GO-2026-5937"],"modified":"2026-07-21T19:19:21.916904551Z","published":"2026-07-07T23:45:05Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-07-07T23:45:05Z","nvd_published_at":null,"cwe_ids":["CWE-693","CWE-73","CWE-918"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/oasdiff/oasdiff/security/advisories/GHSA-2jcc-mxv7-p3f9"},{"type":"WEB","url":"https://github.com/oasdiff/oasdiff/pull/832"},{"type":"WEB","url":"https://github.com/oasdiff/oasdiff/pull/974"},{"type":"WEB","url":"https://github.com/oasdiff/oasdiff/pull/975"},{"type":"PACKAGE","url":"https://github.com/oasdiff/oasdiff"}],"affected":[{"package":{"name":"github.com/oasdiff/oasdiff","ecosystem":"Go","purl":"pkg:golang/github.com/oasdiff/oasdiff"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.13.2"},{"fixed":"1.18.1"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 1.18.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-2jcc-mxv7-p3f9/GHSA-2jcc-mxv7-p3f9.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"}]}