Path Traversal in @Backstage Plugin-Proxy-Backend

CVE-2026-106491

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.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published .

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-106491?
CVE-2026-106491 is a medium-severity vulnerability in @Backstage Plugin-Proxy-Backend, classified under Improper Input Validation. CVSS score: 6.4/10. Published 2026-10-06.
How severe is CVE-2026-106491?
Medium severity. CVSS v3 base score is 6.4 out of 10.