CVE-2026-106457: Insufficient Audience Validation in @backstage/plugin-auth-backend-module-cloudflare-access-provider
Summary
CVE-2026-106457: Backstage: Insufficient audience validation in the Cloudflare Access auth provider. Affects @backstage/plugin-auth-backend-module-cloudflare-access-provider versions >= 0.1.0, < 0.5.0. Fixed in 0.5.0. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
The @backstage/plugin-auth-backend-module-cloudflare-access-provider is a plugin for Backstage, an open platform for building developer portals. This plugin facilitates authentication via Cloudflare Access, allowing organizations to manage user access securely. However, it has a vulnerability that can allow unauthorized access if not properly configured.
Vulnerability Detail
The vulnerability arises from insufficient audience validation in the Cloudflare Access auth provider. While the provider verifies a token's signature and team issuer, it fails to ensure that the token was specifically issued for the Backstage application. This oversight allows a user with a valid token from another application within the same Cloudflare Zero Trust team to authenticate to Backstage, potentially leading to unauthorized access based on the permissions assigned to that identity.
How To Fix
Latest published version: 0.5.1 as of 23 Oct 2026
npm install @backstage/plugin-auth-backend-module-cloudflare-access-provider@0.5.1Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.5.0
This is the first release that contains the fix.
npm install @backstage/plugin-auth-backend-module-cloudflare-access-provider@0.5.0Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, restrict access to the Backstage auth endpoint to the intended Cloudflare Access application. Alternatively, you can implement a custom authenticator that validates the application audience or disable the provider until the patched version is deployed.
Conclusion
In summary, the CVE-2026-106457 vulnerability in the @backstage/plugin-auth-backend-module-cloudflare-access-provider poses a risk of unauthorized access due to insufficient audience validation. It is crucial to upgrade to the patched version and implement recommended workarounds to mitigate this risk.
See every vulnerability recorded for @backstage/plugin-auth-backend-module-cloudflare-access-provider →
FAQ
The CVSS score of this vulnerability is 6.8, indicating a moderate severity level.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
If exploited, this vulnerability could allow unauthorized users to access the Backstage application, potentially leading to data exposure or unauthorized actions within the application.
Yes, a patch is available in version 0.5.0 of the @backstage/plugin-auth-backend-module-cloudflare-access-provider.
If immediate upgrading is not possible, implement the suggested workarounds to restrict access or validate the application audience.
