Authorization-code theft via URL userinfo allowlist bypass
Published Mar 12, 2026 · Updated Mar 12, 2026
Open redirect in Backstage @backstage/plugin-auth-backend before 0.27.1 allows remote attackers to steal OAuth authorization codes. OidcService compares each raw redirect URI against allowedRedirectUriPatterns, so URL userinfo syntax preserves an allowed-looking prefix while the parsed host is attacker-controlled. Exploitation requires an enabled experimental registration feature and victim consent, after which the code can be exchanged for a valid access token.
Summary
What happened
Open redirect in Backstage @backstage/plugin-auth-backend before 0.27.1 allows remote attackers to steal OAuth authorization codes. OidcService compares each raw redirect URI against allowedRedirectUriPatterns, so URL userinfo syntax preserves an allowed-looking prefix while the parsed host is attacker-controlled. Exploitation requires an enabled experimental registration feature and victim consent, after which the code can be exchanged for a valid access token.
The record
- CVE
- CVE-2026-32235
- Published
- Mar 12, 2026
- Updated
- Mar 12, 2026
- Vendor
- Backstage
- Product
- @backstage/plugin-auth-backend
- Classifications
- CWE-601, CWE-20, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 12, 2026CVE publishedPublication date reported by the CVE source.
- Mar 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.27.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo