Backstage: Insufficient audience validation in the Cloudflare Access auth provider

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-106457
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 21:17:16 UTC
Updated2026-10-06 21:17:16 UTC
DescriptionBackstage is an open framework for building developer portals. From 0.1.0 until 0.5.0, the @backstage/plugin-auth-backend-module-cloudflare-access-provider package is affected by insufficient audience validation in the cloudflare access auth provider. The Cloudflare Access auth provider verifies a token's signature and team issuer, but affected versions do not verify that the token was issued for the Backstage application. A user holding a valid token for another Access application in the same Cloudflare Zero Trust team may therefore be able to authenticate to Backstage if that token reaches the auth endpoint without the Backstage application's audience already being enforced upstream. Cloudflare Access normally evaluates the protected application before forwarding requests. This issue is fixed in version 0.5.0.

Risk And Classification

Primary CVSS: v3.1 6.8 MEDIUM from [email protected]

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

Problem Types: CWE-287 | CWE-287 CWE-287: Improper Authentication

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED6.8MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Backstage Backstage affected >= 1.26.0, < 1.55.0 Not specified
CNA @backstage Plugin-auth-backend-module-cloudflare-access-provider affected >= 0.1.0, < 0.5.0 Not specified

References

ReferenceSourceLinkTags
github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f75... [email protected] github.com
github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7 [email protected] github.com
github.com/backstage/backstage/releases/tag/v1.55.0 [email protected] github.com
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