CVE-2026-13097 in FreeIPA
Summary
by MITRE • 08/20/2026
A privilege escalation flaw was found in FreeIPA. The uniqueness constraint enforced on Kerberos principal name attributes in the 389-ds directory server does not properly account for equivalent representations of the same principal name, allowing a user with sufficient LDAP write privileges to create a service principal that impersonates an existing privileged one. This can lead to unauthorized acquisition of Kerberos service tickets for sensitive services, potentially resulting in full domain compromise.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified within FreeIPA stems from a fundamental flaw in how the underlying 389-ds directory server handles uniqueness constraints on Kerberos principal name attributes. In standard LDAP implementations, unique constraints are designed to prevent duplicate entries for specific attribute values, ensuring data integrity and preventing conflicts. However, this implementation fails to account for equivalent representations of the same principal name. This oversight means that while two identical strings cannot be created as distinct principals, variations in formatting or encoding that represent the exact same logical identity can bypass these checks. Consequently, an attacker with sufficient LDAP write privileges can exploit this gap by crafting a service principal entry that is technically distinct according to the directory server's strict string comparison but functionally equivalent to an existing privileged account from the perspective of the Kerberos authentication system.
This technical flaw enables a severe privilege escalation scenario where a lower-privileged user or compromised application with LDAP write access can create a malicious service principal that impersonates a high-privilege entity. By leveraging this duplicate entry, the attacker gains the ability to request and acquire Kerberos service tickets for sensitive services associated with the privileged account. Since Kerberos relies on these tickets to authenticate users to network resources without transmitting passwords over the wire, obtaining valid tickets for an administrative or system-level principal effectively grants the attacker the same level of access as that privileged identity. This bypasses traditional authentication controls and allows the adversary to operate under the guise of a trusted service account, making detection significantly more difficult through standard logging mechanisms which may not distinguish between legitimate usage by the original principal and malicious activity via the impersonated one.
The operational impact of this vulnerability is critical, as it can lead directly to full domain compromise. Once an attacker has acquired valid Kerberos tickets for privileged services, they can access sensitive data, modify configurations, install backdoors, or move laterally across the network with elevated permissions. This undermines the core security model of FreeIPA and Active Directory environments that rely on strict identity separation. The ability to impersonate existing principals also facilitates persistence, as the attacker can maintain long-term access by renewing tickets for these service accounts without triggering typical alerts associated with new account creation or password changes.
Mitigation strategies must address both the immediate configuration weaknesses and broader architectural defenses. Administrators should ensure that FreeIPA is updated to versions where this uniqueness constraint logic has been corrected to normalize principal names before checking for duplicates, thereby preventing equivalent representations from being created as separate entries. Additionally, implementing strict least-privilege policies regarding LDAP write access can reduce the attack surface by limiting which users or services have the ability to create new principals. Monitoring and auditing should be enhanced to detect unusual patterns in Kerberos ticket requests, particularly those involving service accounts that are not typically active during certain hours or from unexpected source IPs. Furthermore, enabling advanced logging for directory server operations related to principal creation can help identify attempts to exploit this flaw before they result in successful impersonation. Aligning with industry standards such as CWE-269 Improper Privilege Management and ATT&CK technique T1550 Use Alternate Authentication Material provides a framework for understanding the nature of this vulnerability and ensuring that detection rules are tuned to catch similar lateral movement or privilege escalation attempts across the environment.