CVE-2026-106491
mediumpriority · track · 0EPSS 0.003 · 20 %ileUSEPSS · scored 2026-10-27
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
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base score 0–10 · higher = more severe · hover a vector to decode
ssvc
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weaknesses
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affected products (3)
Products and version ranges known to be affected.
- linuxfoundation backstage/plugin-proxy-backend< 0.6.17nvdUScpe:2.3:a:linuxfoundation:backstage\/plugin-proxy-backend:*:*:*:*:*:*:*:*
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-9ghw-48h5-v2w5Backstage: Improper input validation in proxy-backend2026-10-07ghsa · osvUS
### Impact 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. ### Patches Patched in `@backstage/plugin-proxy-backend` version `0.6.17` ### Workarounds - Deploy a reverse proxy or WAF in front of Backstage that normalizes request paths before they reach the backend.
sources
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references (3) nvd
External citations — patches, advisories, analysis.
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