VulnerabilityAnalyzed

CVE-2026-106491

Prior to 0.6.17, the @backstage/plugin-proxy-backend package is affected by improper input validation in proxy-backend.

MEDIUM 6.4EPSS 0.27%

Does this matter?

Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.

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 3.1: 6.4 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
EPSS: 0.27% probability · 20th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-20, CWE-22
Affected: linuxfoundation/backstage\/plugin-proxy-backend · linuxfoundation/backstage
Source: security-advisories@github.com

EPSS trend

EPSS moved from 0.3% on 7 October 2026 to 0.3% on 26 October 2026.

References

https://github.com/backstage/backstage/commit/233287d0ce3133e41549bf92a7470c940a41753cPatch
https://github.com/backstage/backstage/releases/tag/v1.54.6Patch, Release Notes
https://github.com/backstage/backstage/security/advisories/GHSA-9ghw-48h5-v2w5Mitigation, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.