{"id":"CVE-2026-106491","aliases":["GHSA-9ghw-48h5-v2w5"],"url":"https://o3.security/vulnerability/CVE-2026-106491","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.","published":"2026-10-06T20:45:08.067Z","modified":"2026-10-21T02:50:18.030868360Z","cvss":{"score":6.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"npm","name":"@backstage/plugin-proxy-backend","fixedVersion":"0.6.17"}],"fix":{"url":"https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c","label":"backstage/backstage@233287d"},"references":[{"type":"WEB","url":"https://github.com/backstage/backstage/releases/tag/v1.54.6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/106xxx/CVE-2026-106491.json"},{"type":"ADVISORY","url":"https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-106491"},{"type":"FIX","url":"https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c"},{"type":"PACKAGE","url":"https://github.com/backstage/backstage"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:50:18.030868360Z"}}