A newly discovered security chain in FreeIPA and 389 Directory Server allows an anonymous client—one that has never authenticated—to craft a reusable administrator-level Kerberos credential. This vulnerability affects default installations and could let attackers gain full administrative control.
What the Vulnerabilities Are
FreeIPA, an identity management system for Linux domains, relies on its directory database from 389 Directory Server. Red Hat revealed two interlinked flaws that together permit an attacker to create a Kerberos identity and write it into the administrators group—even without prior login. One flaw is in FreeIPA’s own access-control rule (ACI) which allows users to write data for their one-time-password tokens without logging in, without restrictions on additional write actions. The second flaw comes from 389 Directory Server, which uses a rule designed to match a client’s authenticated name against a stored owner attribute. For unauthenticated clients, the name is empty. If the owner field is also empty, the server considers the check passed, allowing write operations.
Through this chain, an anonymous client can insert both a Kerberos principal and password entry into the directory, thereby gaining admin-group membership or equivalent privileges. The identity they inject must not already exist—earlier protections against impersonation of existing accounts were added in a prior patch. But this new chain works under a name of the attacker’s choosing and achieves the same high-privilege access.
Other Flaws and Severity Levels
Red Hat has cataloged the FreeIPA flaw as CVE-2026-76578, giving it a critical severity with a preliminary CVSS score of 9.8. The 389-ds vulnerability is CVE-2026-76560, rated important, because the specific rule that enables this behavior is shipped by default in FreeIPA. A separate bug has also been disclosed—CVE-2026-79678—where a command line tool ’idp-add’ evaluates user-supplied strings via Python’s eval() before permission checks, exposing sensitive environment variables and memory under certain deployments. That one scores 8.1 in severity.
What Has Been Fixed and What Still Needs Attention
FreeIPA version 4.13.4 includes patches for both FreeIPA and the directory-server issues. Various Red Hat advisories—especially one for version “389-ds-base” on RHEL 10—address these flaws. In Fedora, updates are undergoing quality assurance. As of September 8, the ipa packages on RHEL are not yet fixed, and RHEL 9 has no advisory confirming a resolution.
Mitigations and Recommendations
Until fixes are broadly deployed, Red Hat urges administrators to restrict access to LDAP services (ports 389 and 636) to trusted hosts via network controls. Disabling anonymous LDAP binds stops this chain, though admins must check for dependencies. The ’idp-add’ flaw lacks configuration-based mitigation—only installing a patched version will address it. For containerized setups, verifying that temporary credentials used at installation are removed from the runtime environment is critical.
Unanswered Questions
Several key issues remain unclear. It’s not yet known whether applying directory-server updates alone protects systems whose FreeIPA packages are still outdated. Also, there is no published guidance yet on detecting whether an attacker has already used this flaw, or whether malicious entries can or should be cleaned up.
This chain was identified by researchers including Gia Bui of Calif with involvement from Anthropic. As of now, there is no evidence that the vulnerabilities have been exploited in the wild.
The FreeIPA/389-ds flaw chain underscores how intertwined misconfigurations and flawed default rules can lead to devastating privilege escalation. Administrators should prioritize patching FreeIPA 4.13.4 and related directory services—or else rapidly apply temporary mitigation strategies. Going forward, supply-chain and config-default research will need to focus not just on code flaws, but on how default ACLs or ACIs can be weaponized in systems thought to be safe.
