Answer in brief
CVE-2026-106491 records a Medium severity (CVSS 6.4) vulnerability in Backstage: Improper input validation in proxy-backend. The current sources do not mark it as known exploited. The current feed maps backstage/backstage (generic), @backstage/plugin-proxy-backend (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.4. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps backstage/backstage (generic), @backstage/plugin-proxy-backend (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| backstage/backstagegeneric | <1.54.6 | 1.54.6 |
| @backstage/plugin-proxy-backendgeneric | <0.6.17 | 0.6.17 |
Published upstream
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 6, 2026
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.
Quoted source text, attributed separately from HOL analysis.