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CVE-2026-106457— Backstage: Insufficient audience validation in the Cloudflare Access auth provider

Quick assessment

Affected
backstage backstage
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Backstage 是一个用于构建开发者门户的开放框架。在版本 0.1.0 至 0.5.0 之间， 包存在云访问身份验证提供程序中的受众（audience）验证不足的问题。 Cloudflare Access 身份验证提供程序会验证令牌的签名和团队签发者，但在受影响的版本中，并未验证该令牌是否是为 Backstage 应用程序签发的。因此，如果持有同一 Cloudflare Zero Trust 团队中其他有效应用程序令牌的用户的令牌未经上游强制实施 Backstage 应用程序的受众限制就直接到达身份验证端点，则

CVSS 6.8 · Medium
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I. Basic Information for CVE-2026-106457

Vulnerability Information
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Vulnerability Title
Backstage: Insufficient audience validation in the Cloudflare Access auth provider
Source: CVE Program / CVE List V5
Vulnerability Description
Backstage 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
backstage backstage >= 1.26.0, < 1.55.0 -
@backstage plugin-auth-backend-module-cloudflare-access-provider >= 0.1.0, < 0.5.0 -

II. Public POCs for CVE-2026-106457

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III. Intelligence Information for CVE-2026-106457

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Other References for CVE-2026-106457 (3)

Same Patch Batch · backstage · 2026-10-06 · 18 CVEs total

CVE-2026-106459 8.5 HIGH Backstage: Improper input validation in Sentry scaffolder actions
CVE-2026-106486 8.5 HIGH Backstage: Improper filesystem validation in Bitbucket pull-request scaffolder actions
CVE-2026-106488 8.1 HIGH Backstage: Improper authentication in the OIDC provider
CVE-2026-106455 7.7 HIGH Backstage: Improper validation of MkDocs plugin configuration in TechDocs
CVE-2026-106492 7.6 HIGH Backstage: Improper preservation of access restrictions during service credential delegati
CVE-2026-106460 6.8 MEDIUM Backstage: Explicit negative email verification can be ignored during shared OAuth profile
CVE-2026-106458 6.5 MEDIUM Backstage: Inconsistent repository filtering in Bitbucket Server catalog event updates
CVE-2026-106490 6.5 MEDIUM Backstage: Improper input validation in TechDocs static content requests
CVE-2026-106489 6.5 MEDIUM Backstage: Improper authorization enforcement for TechDocs static content
CVE-2026-106462 6.4 MEDIUM Backstage: Scaffolder credential handling may allow unintended GitHub authentication fallb
CVE-2026-106491 6.4 MEDIUM Backstage: Improper input validation in proxy-backend
CVE-2026-106463 5.4 MEDIUM Backstage: Improper authorization in GitLab organizational user ingestion
CVE-2026-106456 4.8 MEDIUM Backstage: Inconsistent credential enforcement for overlapping proxy routes
CVE-2026-106494 4.4 MEDIUM Backstage: Improper input validation in cloud storage URL readers
CVE-2026-106461 4.3 MEDIUM Backstage: Incorrect authorization in scaffolder task listing
CVE-2026-106487 3.5 LOW Backstage: Unsupported catalog cluster authentication mode in kubernetes backend
CVE-2026-106493 3.0 LOW Backstage: Cloud storage catalog locations may cross configured storage boundaries

IV. Related Vulnerabilities

Same product: backstage
Same vendor: backstage
Same weakness: CWE-287

V. Comments for CVE-2026-106457

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