Medium 6.8Published Oct 6, 2026

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

Updated under an hour ago (2026-10-19 07:30 UTC)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 6.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-287
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Undergoing Analysis
Record last updated: Oct 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

backstage backstage backstage:backstage (from the name)	from 1.26.0, < 1.55.0	CNA record
@backstage plugin-auth-backend-module-cloudflare-access-provider backstage:plugin_auth_backend_module_cloudflare_access_provider (from the name)	from 0.1.0, < 0.5.0	CNA record

References

https://github.com/backstage/backstage/security/advisories/GHSA-q333-f498-w2x7x-refsource-confirm
https://github.com/backstage/backstage/commit/ed9034cacd9def3b3674f0a764fe992f751e204dx-refsource-misc
https://github.com/backstage/backstage/releases/tag/v1.55.0x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.