CVE-2026-106456

Undergoing Analysis Undergoing Analysis - In Progress

BaseFortify

Publication date: 2026-10-06

Last updated on: 2026-10-07

Assigner: GitHub, Inc.

Description

Backstage is an open framework for building developer portals. From 0.5.0 until 0.6.18, the @backstage/plugin-proxy-backend package is affected by inconsistent credential enforcement for overlapping proxy routes. An operator can configure overlapping proxy paths with different credential requirements. When a parent path permits unauthenticated access and a nested path requires credentials, the parent exemption can also cover requests handled by the nested proxy. An unauthenticated caller may therefore reach the nested upstream through Backstage, including with static upstream credentials configured for that proxy. This issue is fixed in version 0.6.18.

CVSS Scores

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Meta Information

Published

2026-10-06

Last Modified

2026-10-07

Generated

2026-10-19

AI Q&A

2026-10-07

EPSS Evaluated

2026-10-18

NVD

CVE-2026-106456

Affected Vendors & Products

Vendor	Product	Version / Range
backstage	backstage	>= 1.28.0, < 1.55.0
@backstage	plugin-proxy-backend	>= 0.5.0, < 0.6.18

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-863	The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

Executive Summary

Backstage versions 0.5.0 to 0.6.18 have a flaw in the @backstage/plugin-proxy-backend package where overlapping proxy routes with different credential requirements are not enforced consistently. If a parent path allows unauthenticated access and a nested path requires credentials, the parent exemption may incorrectly cover requests to the nested path. This could let unauthenticated users access protected upstream services through Backstage, even if those services require authentication.

Detection Guidance

To detect this vulnerability, check if your Backstage instance is running a version of @backstage/plugin-proxy-backend between 0.5.0 and 0.6.17. Inspect proxy route configurations for overlapping paths with inconsistent credential enforcement. Verify if unauthenticated requests to parent paths bypass authentication for nested paths.

Impact Analysis

If you use Backstage with the affected plugin version, an attacker could bypass authentication requirements for sensitive proxy routes. This may allow unauthorized access to internal services, data leaks, or misuse of configured static credentials for proxied services.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Unauthenticated access to protected routes may result in non-compliance with data protection controls and audit requirements.

Mitigation Strategies

Update the @backstage/plugin-proxy-backend package to version 0.6.18 or later to address the credential enforcement issue.

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