{"id":"EUVD-2026-93990","revision":null,"records":[{"revision":"6c017bab183449339537bd46f8523794","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-106457","aliases":[],"title":"Backstage: Insufficient audience validation in the Cloudflare Access auth provider","description":"Backstage is an open framework for building developer portals. From 0.1.0 until 0.5.0, the @backstage/plugin-auth-backend-module-cloudflare-access-provider package is affected by insufficient audience validation in the cloudflare access auth provider. The Cloudflare Access auth provider verifies a token's signature and team issuer, but affected versions do not verify that the token was issued for the Backstage application. A user holding a valid token for another Access application in the same Cloudflare Zero Trust team may therefore be able to authenticate to Backstage if that token reaches the auth endpoint without the Backstage application's audience already being enforced upstream. Cloudflare Access normally evaluates the protected application before forwarding requests. This issue is fixed in version 0.5.0.","state":0,"publishedAt":"2026-10-06T20:13:26.801+00:00","modifiedAt":"2026-10-07T15:09:19.708+00:00","affected":[{"ecosystem":"Vendor product","name":"backstage","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"backstage\",\n                    \"product\": \"backstage\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 1.26.0, < 1.55.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"plugin-auth-backend-module-cloudflare-access-provider","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"@backstage\",\n                    \"product\": \"plugin-auth-backend-module-cloudflare-access-provider\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 0.1.0, < 0.5.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":"MEDIUM"}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7","https://github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f751e204d","https://github.com/backstage/backstage/releases/tag/v1.55.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-106457","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-106457","identifiers":["CVE-2026-106457"]},"retained":false,"historicalAffected":[]},{"revision":"1bcf99dec5074037b327875318b9f765","observedAt":"2026-10-30T01:52:16.555+00:00","statement":{"source":"euvd","id":"EUVD-2026-93990","aliases":["CVE-2026-106457","GHSA-q333-f498-w2x7"],"title":"Backstage is an open framework for building developer portals. 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This issue is fixed in version 0.5.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":null}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7","https://github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f751e204d","https://github.com/backstage/backstage/releases/tag/v1.55.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-93990","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Oct 6, 2026, 8:13:26 PM","dateUpdated":"Oct 7, 2026, 3:09:19 PM"},"relatedAdvisories":[],"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-2026-93990","identifiers":["EUVD-2026-93990","CVE-2026-106457","GHSA-q333-f498-w2x7"]},"retained":false,"historicalAffected":[]},{"revision":"6c416c39d6b2441383f899970aa8ec78","observedAt":"2026-10-29T05:48:21.551+00:00","statement":{"source":"nvd","id":"CVE-2026-106457","aliases":[],"title":"Backstage is an open framework for building developer portals. From 0.1.0 until 0.5.0, the @backstage/plugin-auth-backend-module-cloudflare-access-provider package is affected by insufficient audience validation in the cloudflare access aut…","description":"Backstage is an open framework for building developer portals. From 0.1.0 until 0.5.0, the @backstage/plugin-auth-backend-module-cloudflare-access-provider package is affected by insufficient audience validation in the cloudflare access auth provider. The Cloudflare Access auth provider verifies a token's signature and team issuer, but affected versions do not verify that the token was issued for the Backstage application. A user holding a valid token for another Access application in the same Cloudflare Zero Trust team may therefore be able to authenticate to Backstage if that token reaches the auth endpoint without the Backstage application's audience already being enforced upstream. Cloudflare Access normally evaluates the protected application before forwarding requests. This issue is fixed in version 0.5.0.","state":0,"publishedAt":"2026-10-06T21:17:16.083+00:00","modifiedAt":"2026-10-27T20:48:50.79+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":6.8,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f751e204d","https://github.com/backstage/backstage/releases/tag/v1.55.0","https://github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-106457","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-287"],"productCriteria":["cpe:2.3:a:linuxfoundation:backstage\\/plugin-auth-backend-module-cloudflare-access-provider:*:*:*:*:*:node.js:*:*","cpe:2.3:a:linuxfoundation:backstage:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-10-06T21:17:16.083","lastModified":"2026-10-27T20:48:50.790"},"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-2026-106457","identifiers":["CVE-2026-106457"]},"retained":false,"historicalAffected":[]},{"revision":"87bb80da8e9c4569bf0ab5bdd5f2ffa3","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-q333-f498-w2x7","aliases":["CVE-2026-106457"],"title":"Backstage: Insufficient audience validation in the Cloudflare Access auth provider","description":"### Impact\n\nThe Cloudflare Access auth provider verifies a token's signature and team issuer, but affected versions do not verify that the token was issued for the Backstage application. A user holding a valid token for another Access application in the same Cloudflare Zero Trust team may therefore be able to authenticate to Backstage if that token reaches the auth endpoint without the Backstage application's audience already being enforced upstream.\n\nCloudflare Access normally evaluates the protected application before forwarding requests. The reported reproduction exercises the provider directly and does not demonstrate bypass through the ordinary Cloudflare-protected Backstage URL. Relevant deployment topologies include direct origin access, alternate routes around the intended Access application, or another proxy forwarding the assertion unchanged.\n\nA successful sign-in also depends on the deployment's sign-in resolver mapping the presented identity to a Backstage user. The resulting impact depends on the permissions assigned to that identity.\n\n### Patches\n\nUpgrade `@backstage/plugin-auth-backend-module-cloudflare-access-provider` to version `0.5.0` or later. The fixed package is available in [Backstage v1.55.0](https://github.com/backstage/backstage/releases/tag/v1.55.0).\n\nThis is a breaking configuration change. Before upgrading, set `auth.providers.cfaccess.audience` to the Audience (AUD) tag for the Backstage application in Cloudflare Zero Trust:\n\n```yaml\nauth:\n  providers:\n    cfaccess:\n      teamName: example\n      audience: ${AUTH_CFACCESS_AUDIENCE}\n```\n\n### Workarounds\n\n- Restrict access to the Backstage auth endpoint to the intended Cloudflare Access application.\n- Use a custom authenticator that validates the application audience.\n- Disable the provider until the patched package can be deployed.","state":0,"publishedAt":"2026-10-07T20:25:25+00:00","modifiedAt":"2026-10-07T20:30:04.8329172+00:00","affected":[{"ecosystem":"npm","name":"@backstage/plugin-auth-backend-module-cloudflare-access-provider","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0.1.0"},{"kind":"fixed","version":"0.5.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7","https://nvd.nist.gov/vuln/detail/CVE-2026-106457","https://github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f751e204d","https://github.com/backstage/backstage","https://github.com/backstage/backstage/releases/tag/v1.55.0"],"sourceUrl":"https://github.com/advisories/GHSA-q333-f498-w2x7","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-q333-f498-w2x7","identifiers":["GHSA-q333-f498-w2x7","CVE-2026-106457"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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