Bug 2539284 (CVE-2026-96446)

Summary: CVE-2026-96446 keycloak-services: keycloak-services: PAR single-use bypass via prompt=none silent authentication path
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: aschwart, aszczucz, boliveir, drichtar, mposolda, pjindal, rmartinc, ssilvert, sthorger, vmuzikar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Pushed Authorization Request PAR implementation of Keycloak. The issue occurs when the silent authentication path prompt=none is used, which allows the authorization process to skip certain steps if a user is already logged in. Due to this bypass, the security rule that ensures a pushed request URI is used only once is not enforced. An attacker could potentially reuse a request URI to obtain multiple authorization codes for a user who is already signed in, violating security standards like FAPI-2.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-23 09:33:20 UTC 
A flaw was found in Keycloaks Pushed Authorization Request PAR implementation. The single-use enforcement for PAR request URIs, as required by RFC 9126 section 4, is bypassed when using the silent authentication path prompt=none. When an existing SSO session is present, the authorization endpoint short-circuits directly to the successful-flow redirect handler. In this specific code path, the PAR consumption logic is never triggered, meaning the pushed request object is not removed from storage after use.
Exploitation requires that the realm has PAR enabled, the attacker has valid client credentials to push an authorization request, and an active SSO session exists for the target user. A successful attacker can replay the request_uri multiple times to mint distinct, fully redeemable authorization codes for the same user without requiring the resource owner to re-authenticate. This allows for unauthorized token generation and violates the single-use guarantee required for FAPI-2 and RFC 9126 compliant deployments.