Bug 2509763 (CVE-2026-18572)

Summary: CVE-2026-18572 keycloak-services: keycloak-services: UMA claim token can override authorization time-policy evaluation attributes
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: anujha, aschwart, asoldano, aszczucz, bbaranow, bmaxwell, boliveir, bstansbe, dlofthou, drichtar, istudens, ivassile, iweiss, mosmerov, mposolda, msvehla, nwallace, pberan, pesilva, pjindal, pmackay, rmartinc, rstancel, ssilvert, sthorger, thjenkin, vdosoudi, vmuzikar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Keycloak provides authorization services that allow administrators to restrict access to resources based on time policies (for example, only allowing access during business hours). A flaw was discovered where a user can include a fake time value in their authorization request that overrides the actual server time. This allows the user to bypass these time-based restrictions and access protected resources at unauthorized times.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-31 12:33:33 UTC
A vulnerability was found in Keycloak where authenticated users can bypass authorization services time policies. When requesting a User-Managed Access (UMA) permission, a caller can supply a claim token containing forged kc.time.date_time values. Keycloak merges these caller-supplied claims after the server-generated time attributes, allowing the forged values to overwrite the server clock during policy evaluation. This allows an attacker to obtain Resource Permission Tokens (RPTs) outside of the time windows configured by administrators, effectively defeating temporal access controls such as maintenance windows or off-hours access denials.