{"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":"Backstage is an open framework for building developer portals. Prior to 0.27.1, the 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. A 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. This requires victim interaction and that one of the experimental features is explicitly enabled, which is not the default. This vulnerability is fixed in 0.27.1.","published":"2026-03-12T18:35:06.325Z","modified":"2026-08-07T11:31:01.430145740Z","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":null,"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:01.430145740Z"}}