High [CVE-2026-73563] @backstage/plugin-auth-backend: Backstage: Unauthenticated OAuth account takeover via `redirect_uri` allowlist bypass
This high-severity Red Hat Linux advisory covers CVE-2026-73563 affecting Red Hat Developer Hub, Self-service automation portal 2.
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Summary
A flaw was found in the `@backstage/plugin-auth-backend` component of Backstage. This vulnerability allows an unauthenticated remote attacker to bypass the `redirect_uri` allowlist in the experimental dynamic client registration feature.
By crafting a malicious redirect Uniform Resource Identifier (URI) with a trusted hostname suffix, an attacker can receive an OAuth authorization code, potentially leading to an account takeover. This issue affects deployments that have enabled the experimental features and configured custom wildcard-hostname or protocol-less patterns.
Red Hat Developer Hub (RHDH) and Ansible Automation Portal ship @backstage/plugin-auth-backend, which contains this vulnerability. However, the affected features (experimental dynamic client registration and client ID metadata documents) are disabled by default.
Default RHDH configurations are not affected. Red Hat severity: Important — CVSS 8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N).
Weakness: CWE-1289. Affected Red Hat products: Red Hat Developer Hub; Self-service automation portal 2.
Red Hat does not currently list a fixing RHSA for this CVE.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- Do not enable the experimental dynamic client registration or client ID metadata document features. If these features are currently enabled, review and restrict the allowedRedirectUriPatterns and allowedClientIdPatterns configurations to use fully qualified hostnames with explicit protocols rather than wildcard or protocol-less patterns.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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