CVE-2026-32235
Prior to 0.27.1, the experimental OIDC provider in @backstage/plugin-auth-backend is vulnerable to a redirect URI allowlist bypass.
Does this matter?
Lower severity and a low EPSS score (0.14%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 4.7 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N
- EPSS
- 0.14% probability · 4th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-601
- Affected
- linuxfoundation/backstage
- Source
- security-advisories@github.com
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.