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CVE-2026-9803

5.3 medium SSVC exploitation: none Modified
NVD · CVE.org

A flaw was found in Keycloak's ClientRegistrationAuth component. A remote unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with a malformed 'Authorization: Bearer' header to any client registration endpoint. This can lead to an ArrayIndexOutOfBoundsException, causing the server to return an HTTP 500 error and resulting in a Denial of Service (DoS) for the affected service.

Fix

Patch, vendor advisory and mitigation references on NVD 2

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

  1. First seenCVSS 5.3 · redhatNVD modified 2026-10-26 12:10

Affected (CPE criteria) 1

  • cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*

References 6