Authorization-code interception via prefix-only host validation
Published Jul 31, 2026 · Updated Jul 31, 2026
Policy bypass in Red Hat build of Keycloak allows remote attackers to intercept authorization codes via cleartext HTTP redirects. The secure-client-uris executor checks only the start of a redirect URI instead of validating its host, so localhost-prefixed attacker domains pass the encryption policy. Exploitation requires Dynamic Client Registration, control of such a domain, and user interaction; the bounded impact is disclosure and possible misuse of an authorization code.
Summary
What happened
Policy bypass in Red Hat build of Keycloak allows remote attackers to intercept authorization codes via cleartext HTTP redirects. The secure-client-uris executor checks only the start of a redirect URI instead of validating its host, so localhost-prefixed attacker domains pass the encryption policy. Exploitation requires Dynamic Client Registration, control of such a domain, and user interaction; the bounded impact is disclosure and possible misuse of an authorization code.
The record
- CVE
- CVE-2026-18211
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat build of Keycloak
- Classifications
- CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
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Technologies
Your stack
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Your stack
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