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.

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
backstage backstage affected
Version Status Constraints
>= 1.28.0, < 1.55.0 affected —
@backstage plugin-proxy-backend affected
Version Status Constraints
>= 0.5.0, < 0.6.18 affected —

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Project Subscriptions

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c44e218 cve-icon
https://github.com/backstage/backstage/releases/tag/v1.55.0 cve-icon
https://github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr cve-icon
History

Tue, 06 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
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.
Title Backstage: Inconsistent credential enforcement for overlapping proxy routes
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-06T20:10:41.795Z

Reserved: 2026-10-06T16:49:40.591Z

Link: CVE-2026-106456

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses