{"cve":"CVE-2026-106491","nvd":{"published":"2026-10-06T21:17:18.073","modified":"2026-10-22T14:10:06.117","status":"Analyzed","description":"Backstage is an open framework for building developer portals. Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend. An 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. This issue is fixed in version 0.6.17.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","score":6.4},"cwes":["CWE-20","CWE-22"],"references":["https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c","https://github.com/backstage/backstage/releases/tag/v1.54.6","https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5"],"products":["linuxfoundation:backstage","linuxfoundation:backstage\\/plugin-proxy-backend"],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-106491","score":0.00275,"percentile":0.19664,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-9ghw-48h5-v2w5","url":"https://osv.dev/vulnerability/GHSA-9ghw-48h5-v2w5","summary":"Backstage: Improper input validation in proxy-backend","modified":"2026-10-07T18:15:11.766501419Z","packages":[{"ecosystem":"npm","name":"@backstage/plugin-proxy-backend","purl":"pkg:npm/%40backstage/plugin-proxy-backend","ranges":["<0.6.17"],"fixed":["0.6.17"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}