Bug 2443771 (CVE-2026-3429)

Summary: CVE-2026-3429 org.keycloak.services.resources.account: Improper Access Control Leading to MFA Deletion and Account Takeover in Keycloak Account REST API
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: aschwart, asoldano, bbaranow, bmaxwell, boliveir, brian.stansberry, darran.lofthouse, dosoudil, fjuma, istudens, ivassile, iweiss, mosmerov, mposolda, msvehla, nwallace, pberan, pesilva, pjindal, pmackay, rmartinc, rstancel, smaestri, ssilvert, sthorger, tom.jenkinson, vmuzikar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was identified in the Account REST API of Keycloak that allows a user authenticated at a lower security level to perform sensitive actions intended only for higher-assurance sessions. Specifically, an attacker who has already obtained a victim’s password can delete the victim’s registered MFA/OTP credential without first proving possession of that factor. The attacker can then register their own MFA device, effectively taking full control of the account. This weakness undermines the intended protection provided by multi-factor authentication.
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Description OSIDB Bzimport 2026-03-02 10:03:36 UTC 
Improper Access Control vulnerability in the Account REST API of Keycloak. The flaw is caused by insufficient validation of the authentication Level of Assurance (LoA) before allowing credential management actions. An attacker who has obtained a victim’s primary credentials (username and password) can authenticate at a lower LoA and delete the victim’s registered OTP/MFA credential without completing step-up authentication. The attacker can then register their own MFA device, effectively achieving full account takeover. Exploitation requires network access and valid credentials but no user interaction, resulting in compromise of account integrity and partial confidentiality impact.