{"id":"GHSA-38hq-7x33-php4","revision":null,"records":[{"revision":"b245ef44032a4bd7a163917393d27102","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-73563","aliases":[],"title":"Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass in `@backstage/plugin-auth-backend`","description":"Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriPatterns options. A hostname wildcard can match across URL component boundaries, allowing an attacker-controlled redirect URI with a trusted hostname suffix in its path to pass the allowlist and receive an OAuth authorization code after a victim completes the flow. Patterns without an explicit protocol can match unintended protocols, and redirect URIs containing embedded credentials are accepted after user information is stripped for matching. The features are experimental and disabled by default; only deployments that enable them and configure custom wildcard-hostname or protocol-less patterns are affected. This issue is first fixed in prerelease version 0.29.2.","state":0,"publishedAt":"2026-08-13T17:32:39.535+00:00","modifiedAt":"2026-08-13T18:07:45.624+00:00","affected":[{"ecosystem":"Vendor product","name":"backstage","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"backstage\",\n                    \"product\": \"backstage\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 0.29.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N","score":4.7,"severity":"MEDIUM"}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-38hq-7x33-php4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-73563","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-73563","identifiers":["CVE-2026-73563"]},"retained":false,"historicalAffected":[]},{"revision":"9d8bac110ce540cba2daf010e173a62f","observedAt":"2026-11-07T14:26:52.335+00:00","statement":{"source":"euvd","id":"EUVD-2026-58177","aliases":["CVE-2026-73563","GHSA-38hq-7x33-php4"],"title":"Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob…","description":"Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriPatterns options. A hostname wildcard can match across URL component boundaries, allowing an attacker-controlled redirect URI with a trusted hostname suffix in its path to pass the allowlist and receive an OAuth authorization code after a victim completes the flow. Patterns without an explicit protocol can match unintended protocols, and redirect URIs containing embedded credentials are accepted after user information is stripped for matching. The features are experimental and disabled by default; only deployments that enable them and configure custom wildcard-hostname or protocol-less patterns are affected. This issue is first fixed in prerelease version 0.29.2.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N","score":4.7,"severity":null}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-38hq-7x33-php4"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-58177","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Aug 13, 2026, 5:32:39 PM","dateUpdated":"Aug 13, 2026, 6:07:45 PM"},"relatedAdvisories":[{"id":"RHSA-2026:65155","title":"Red Hat Security Advisory: Ansible plug-ins for Red Hat Developer Hub Product Release Update","vulnerabilityIds":["CVE-2026-67213","CVE-2026-67214","CVE-2026-73563","CVE-2026-73566","CVE-2026-75838","CVE-2026-75899","CVE-2026-75931","CVE-2026-75975","CVE-2026-76172","CVE-2026-84292","CVE-2026-84394"]},{"id":"RHSA-2026:65118","title":"Red Hat Security Advisory: Ansible plug-ins for Red Hat Developer Hub Product Release Update","vulnerabilityIds":["CVE-2026-5079","CVE-2026-67213","CVE-2026-67214","CVE-2026-67313","CVE-2026-67314","CVE-2026-67320","CVE-2026-67321","CVE-2026-73563","CVE-2026-73566","CVE-2026-75838","CVE-2026-75899","CVE-2026-75931","CVE-2026-75975","CVE-2026-76172","CVE-2026-84292","CVE-2026-84394"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-58177","identifiers":["EUVD-2026-58177","CVE-2026-73563","GHSA-38hq-7x33-php4"]},"retained":false,"historicalAffected":[]},{"revision":"a935882110124d188341c95e3832dcfa","observedAt":"2026-10-25T15:19:09.409+00:00","statement":{"source":"nvd","id":"CVE-2026-73563","aliases":[],"title":"Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob…","description":"Backstage is an open framework for building developer portals. Prior to 0.29.2, the experimental dynamic client registration and client ID metadata document features in the @backstage/plugin-auth-backend use full-string matcher.isMatch glob matching for auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns and the auth.experimentalClientIdMetadataDocuments allowedClientIdPatterns and allowedRedirectUriPatterns options. A hostname wildcard can match across URL component boundaries, allowing an attacker-controlled redirect URI with a trusted hostname suffix in its path to pass the allowlist and receive an OAuth authorization code after a victim completes the flow. Patterns without an explicit protocol can match unintended protocols, and redirect URIs containing embedded credentials are accepted after user information is stripped for matching. The features are experimental and disabled by default; only deployments that enable them and configure custom wildcard-hostname or protocol-less patterns are affected. This issue is first fixed in prerelease version 0.29.2.","state":0,"publishedAt":"2026-08-13T18:18:18.803+00:00","modifiedAt":"2026-10-15T20:37:36.21+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N","score":4.7,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1,"severity":"MEDIUM"}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-38hq-7x33-php4"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73563","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-601"],"productCriteria":["cpe:2.3:a:linuxfoundation:backstage\\/plugin-auth-backend:*:*:*:*:*:node.js:*:*"],"sourceDates":{"published":"2026-08-13T18:18:18.803","lastModified":"2026-10-15T20:37:36.210"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-73563","identifiers":["CVE-2026-73563"]},"retained":false,"historicalAffected":[]},{"revision":"ccd7d2516a2a4f6d9f652fb8c1875d52","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-38hq-7x33-php4","aliases":["CVE-2026-73563"],"title":"@backstage/plugin-auth-backend: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass","description":"### Impact\nThe allowlist matching used by the experimental dynamic client registration and client ID metadata document (CIMD) features in `@backstage/plugin-auth-backend` matched glob patterns against the full URL string. A * wildcard could therefore match across URL component boundaries: a pattern such as `https://*.example.com/callback`, intended to allow subdomains of a trusted host, would also match an attacker-controlled URL such as `https://attacker.example/x.example.com/callback`. This applies to `auth.experimentalDynamicClientRegistration.allowedRedirectUriPatterns` as well as the `allowedClientIdPatterns` and `allowedRedirectUriPatterns` options of `auth.experimentalClientIdMetadataDocuments`.\n\nAn attacker could use this to register an OAuth client whose redirect URI points to a host they control while still passing the allowlist, causing authorization codes to be delivered to the attacker when a victim completes an authorization flow. In addition, allowlist patterns without an explicit protocol could match URLs with any protocol, and redirect URIs containing embedded credentials (user:pass@host) were accepted after the credentials were stripped for matching.\n\nThe practical impact is limited. Both features are experimental and disabled by default, and the default allowlist patterns only reference fixed or loopback hosts and are not affected. Deployments are only impacted if they enable one of these features and configure custom allowlist patterns that contain a wildcard in the hostname, or patterns without an explicit protocol.\n\n### Patches\nPatched in `@backstage/plugin-auth-backend` version `0.29.2`. Patterns are now matched against each URL component separately so that wildcards no longer match across the host and path boundary, patterns without an explicit protocol are rejected as invalid configuration, and redirect URIs with embedded credentials are always rejected.\n\nNote that as part of this fix, a wildcard port no longer implicitly matches every path: a pattern such as `http://localhost:*` now only matches the root path. Use `http://localhost:*/*` to allow any port and any path.\n\n### Workarounds\nDisable the experimental features by removing `auth.experimentalDynamicClientRegistration` and `auth.experimentalClientIdMetadataDocuments` from your `app-config`, which is the default configuration. Alternatively, restrict the configured allowlist patterns to fully specified URLs with an explicit protocol and no wildcard in the hostname, which are not affected by this vulnerability.","state":0,"publishedAt":"2026-07-24T16:20:59+00:00","modifiedAt":"2026-08-13T17:55:56.778079+00:00","affected":[{"ecosystem":"npm","name":"@backstage/plugin-auth-backend","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"0.29.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-38hq-7x33-php4","https://github.com/backstage/backstage/commit/274acc51d22a7dd919cdda49d9086cf12c0b8711","https://github.com/backstage/backstage/commit/6370e53bce8b227c63092300594ffde29c006886","https://github.com/backstage/backstage/commit/ef606a85545cb6d765e20afd1ff43ae5407a3660","https://github.com/backstage/backstage/commit/fdc0d2dcd9a571e3839d7f5de4133c4e242a3a41","https://github.com/backstage/backstage","https://github.com/backstage/backstage/releases/tag/v1.53.0"],"sourceUrl":"https://github.com/advisories/GHSA-38hq-7x33-php4","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-38hq-7x33-php4","identifiers":["GHSA-38hq-7x33-php4","CVE-2026-73563"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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