{"schema":"threatline.record/2","record":{"id":"CVE-2026-106491","aliases":["GHSA-9ghw-48h5-v2w5"],"summary":"Backstage: Improper input validation in proxy-backend","details":"### Impact\n\nAn authenticated Backstage user could craft a request URL that causes the proxy-backend to forward the request to a path outside the configured base path on the target server. This is limited to target servers already configured as proxy endpoints and requires Backstage authentication by default.\n\n### Patches\n\nPatched in `@backstage/plugin-proxy-backend` version `0.6.17`\n\n### Workarounds\n\n- Deploy a reverse proxy or WAF in front of Backstage that normalizes request paths before they reach the backend.","categories":["Libraries & packages"],"product":"@backstage/plugin-proxy-backend","vendor":"backstage","ecosystem":"npm","affected_ranges":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-9ghw-48h5-v2w5","source_modified_at":"2026-10-07T17:59:49Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@backstage/plugin-proxy-backend"},"range":"< 0.6.17"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-106491","source_modified_at":"2026-10-07T17:52:11.914Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"backstage","vendor":"backstage","versions":[{"version":"< 1.54.6","status":"affected"}],"defaultStatus":null},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-106491","source_modified_at":"2026-10-07T17:52:11.914Z","fetched_at":"2026-10-23T18:45:31.882637Z","product":"plugin-proxy-backend","vendor":"@backstage","versions":[{"version":"< 0.6.17","status":"affected"}],"defaultStatus":null},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-9ghw-48h5-v2w5","source_modified_at":"2026-10-07T18:15:11.766501419Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"@backstage/plugin-proxy-backend","ecosystem":"npm","purl":"pkg:npm/%40backstage/plugin-proxy-backend"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.6.17"}]}],"versions":[]}],"fixed_versions":[{"source":"GitHub Advisory Database","source_url":"https://github.com/advisories/GHSA-9ghw-48h5-v2w5","source_modified_at":"2026-10-07T17:59:49Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"ecosystem":"npm","name":"@backstage/plugin-proxy-backend"},"version":"0.6.17"},{"source":"OSV","source_url":"https://osv.dev/vulnerability/GHSA-9ghw-48h5-v2w5","source_modified_at":"2026-10-07T18:15:11.766501419Z","fetched_at":"2026-10-23T18:45:31.882637Z","package":{"name":"@backstage/plugin-proxy-backend","ecosystem":"npm","purl":"pkg:npm/%40backstage/plugin-proxy-backend"},"version":"0.6.17"}],"cvss":6.4,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00274,"percentile":0.18805,"score_date":"2026-10-23"},"published_at":"2026-10-06T20:45:08.067Z","modified_at":"2026-10-07T18:15:11.766501419Z","provenance":[{"source":"GitHub Advisory Database","url":"https://github.com/advisories/GHSA-9ghw-48h5-v2w5","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-07T17:59:49Z"},{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-106491","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-07T17:52:11.914Z"},{"source":"OSV","url":"https://osv.dev/vulnerability/GHSA-9ghw-48h5-v2w5","fetched_at":"2026-10-23T18:45:31.882637Z","source_modified_at":"2026-10-07T18:15:11.766501419Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-106491","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["GitHub Advisory Database","CVE List","OSV","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5","tags":["x_refsource_CONFIRM"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-106491","source":"GitHub Advisory Database"},{"source":"CVE List","url":"https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/backstage/backstage/releases/tag/v1.54.6","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-9ghw-48h5-v2w5","source":"GitHub Advisory Database"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-07T17:51:57.186407Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"ecosystem","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-07T18:15:11.766501419Z","content_hash":"a06d7f008a5106db52296ea0bde7781e55fa98ee78dbe469478772204018ce74"}}