{"id":"CVE-2026-32235","aliases":["GHSA-wqvh-63mv-9w92"],"url":"https://o3.security/vulnerability/CVE-2026-32235","summary":"@backstage/plugin-auth-backend: OAuth redirect URI allowlist bypass","details":"### Impact\n\nThe experimental OIDC provider in `@backstage/plugin-auth-backend` is vulnerable to a redirect URI allowlist bypass. Instances that have enabled experimental Dynamic Client Registration or Client ID Metadata Documents and configured `allowedRedirectUriPatterns` are affected.\n\nA specially crafted redirect URI can pass the allowlist validation while resolving to an attacker-controlled host. If a victim approves the resulting OAuth consent request, their authorization code is sent to the attacker, who can exchange it for a valid access token.\n\nThis requires victim interaction and that one of the experimental features is explicitly enabled, which is not the default.\n\n### Patches\n\nUpgrade to `@backstage/plugin-auth-backend` version 0.27.1 or later.\n\n### Workarounds\n\nDisable experimental Dynamic Client Registration and Client ID Metadata Documents features if they are not required.\n\n### References\n\n- [RFC 6749 Section 3.1.2 - Redirection Endpoint](https://datatracker.ietf.org/doc/html/rfc6749#section-3.1.2)","published":"2026-03-12T18:35:06.325Z","modified":"2026-08-12T03:51:40.745823540Z","cvss":{"score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@backstage/plugin-auth-backend","fixedVersion":"0.27.1"}],"fix":{"url":"https://github.com/backstage/backstage/commit/6042dd0c7f0706e0f473dafa92799ecf19c825ec","label":"backstage/backstage@6042dd0"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32235.json"},{"type":"ADVISORY","url":"https://github.com/backstage/backstage/security/advisories/GHSA-wqvh-63mv-9w92"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32235"},{"type":"WEB","url":"https://github.com/backstage/backstage/commit/6042dd0c7f0706e0f473dafa92799ecf19c825ec"},{"type":"PACKAGE","url":"https://github.com/backstage/backstage"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:40.745823540Z"}}