{"id":"GHSA-wqvh-63mv-9w92","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)","aliases":["CVE-2026-32235"],"modified":"2026-03-14T01:56:21.282129Z","published":"2026-03-12T14:50:59Z","database_specific":{"github_reviewed_at":"2026-03-12T14:50:59Z","nvd_published_at":"2026-03-12T19:16:17Z","cwe_ids":["CWE-20","CWE-601"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","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"}],"affected":[{"package":{"name":"@backstage/plugin-auth-backend","ecosystem":"npm","purl":"pkg:npm/%40backstage/plugin-auth-backend"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.27.1"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-wqvh-63mv-9w92/GHSA-wqvh-63mv-9w92.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N"}]}