CVE-2026-32235@backstage/plugin-auth-backend: OAuth redirect URI allowlist bypass
Description
Backstage is an open framework for building developer portals. Prior to 0.27.1, the experimental OIDC provider in @backstage/plugin-auth-backend is vulnerable to a redirect URI allowlist bypass. Instances that have enabled experimental Dynamic Client Registration or Client ID Metadata Documents and configured allowedRedirectUriPatterns are affected. A specially crafted redirect URI can pass the allowlist validation while resolving to an attacker-controlled host. If a victim approves the resulting OAuth consent request, their authorization code is sent to the attacker, who can exchange it for a valid access token. This requires victim interaction and that one of the experimental features is explicitly enabled, which is not the default. This vulnerability is fixed in 0.27.1.
Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.
Affected products and versions
| Vendor | Product | Versions | |
|---|---|---|---|
| @backstage | plugin-auth-backend | < 0.27.1 | |
| linuxfoundation | backstage | ≤ 0.27.0 |
References and patches
CPE matches (NVD) (1)
cpe:2.3:a:linuxfoundation:backstage:*:*:*:*:*:*:*:*≤ 0.27.0