Unsigned OIDC claim injection via JWE policy bypass
Published May 28, 2026 · Updated May 28, 2026
Signature-policy bypass in Red Hat build of Keycloak allows remote attackers to inject unsigned claims into OIDC authorization requests. The authorization endpoint decrypts a JWE request object containing raw JSON and honors its claims without enforcing the client's requestObjectSignatureAlg setting. Exploitation requires a client configured to require signed request objects; the redirect URI allowlist prevents authorization-code or token exfiltration.
Summary
What happened
Signature-policy bypass in Red Hat build of Keycloak allows remote attackers to inject unsigned claims into OIDC authorization requests. The authorization endpoint decrypts a JWE request object containing raw JSON and honors its claims without enforcing the client's requestObjectSignatureAlg setting. Exploitation requires a client configured to require signed request objects; the redirect URI allowlist prevents authorization-code or token exfiltration.
The record
- CVE
- CVE-2026-9793
- Published
- May 28, 2026
- Updated
- May 28, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat build of Keycloak
- Classifications
- CWE-347, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 28, 2026CVE publishedPublication date reported by the CVE source.
- May 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
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
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Technologies
Your stack
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Your stack
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