Bug 2547196 (CVE-2026-106491)

Summary:	CVE-2026-106491 plugin-proxy-backend: plugin-proxy-backend: Request forwarding outside configured base path via crafted URL
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abarbaro, alizardo, dschmidt, ikhan, jchui, jhe, jlanda, kshier, ktsao, nboldt, oaljalju, psrna, rbobbitt, simaishi, stcannon, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Backstage plugin-proxy-backend component. An authenticated remote attacker can exploit improper input validation by submitting a specially crafted request URL to the proxy backend. This causes the proxy service to forward requests to endpoints outside the configured base path on target servers, potentially leading to unauthorized access to restricted endpoints or sensitive data.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-06 20:52:18 UTC

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.