A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.
Metrics
Affected Vendors & Products
References
History
Thu, 28 May 2026 01:45:00 +0000
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| First Time appeared |
Redhat build Of Keycloak
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| Vendors & Products |
Redhat build Of Keycloak
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Thu, 28 May 2026 00:15:00 +0000
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| Metrics |
threat_severity
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threat_severity
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Wed, 27 May 2026 17:30:00 +0000
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ssvc
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Wed, 27 May 2026 14:15:00 +0000
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| Description | A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation. | |
| Title | Keycloak: keycloak: privilege escalation due to oversized subject_token jwt | |
| First Time appeared |
Redhat
Redhat build Keycloak |
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| Weaknesses | CWE-1284 | |
| CPEs | cpe:/a:redhat:build_keycloak: | |
| Vendors & Products |
Redhat
Redhat build Keycloak |
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| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: redhat
Published: 2026-05-27T12:56:00.858Z
Updated: 2026-05-27T15:29:26.036Z
Reserved: 2026-05-27T12:39:12.284Z
Link: CVE-2026-9704
Updated: 2026-05-27T15:29:23.173Z
Status : Awaiting Analysis
Published: 2026-05-27T14:17:40.480
Modified: 2026-05-27T14:54:20.160
Link: CVE-2026-9704