Backstage: Inconsistent credential enforcement for overlapping proxy routes

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-106456
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 21:17:15 UTC
Updated2026-10-06 21:17:15 UTC
DescriptionBackstage 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.

Risk And Classification

Primary CVSS: v3.1 4.8 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED4.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Backstage Backstage affected >= 1.28.0, < 1.55.0 Not specified
CNA @backstage Plugin-proxy-backend affected >= 0.5.0, < 0.6.18 Not specified

References

ReferenceSourceLinkTags
github.com/backstage/backstage/security/advisories/GHSA-472h-9c5j-prrr [email protected] github.com
github.com/backstage/backstage/releases/tag/v1.55.0 [email protected] github.com
github.com/backstage/backstage/commit/9df92923ac32558bb80edeceafd8de780c... [email protected] github.com
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