CVE-2026-106491: Backstage: Improper input validation in proxy-backend

October 7, 2026

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.

References

github.com/advisories/GHSA-9ghw-48h5-v2w5
github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753c
github.com/backstage/backstage/releases/tag/v1.54.6
github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5
nvd.nist.gov/vuln/detail/CVE-2026-106491

Code Behaviors & Features

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