{"id":"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.","aliases":["CVE-2026-106491"],"modified":"2026-10-07T18:15:11.766501419Z","published":"2026-10-07T17:59:49Z","database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-10-07T17:59:49Z","nvd_published_at":"2026-10-06T21:17:18Z","cwe_ids":["CWE-20","CWE-22"]},"references":[{"type":"WEB","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":"WEB","url":"https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c"},{"type":"PACKAGE","url":"https://github.com/backstage/backstage"},{"type":"WEB","url":"https://github.com/backstage/backstage/releases/tag/v1.54.6"}],"affected":[{"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"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9ghw-48h5-v2w5/GHSA-9ghw-48h5-v2w5.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"}]}