CVE-2025-11561 is a vulnerability discovered in Red Hat Enterprise Linux 10 that affects the integration between Active Directory (AD) and the System Security Services Daemon (SSSD), a key component used for identity and authentication services on Linux systems. The root cause lies in the default configuration of SSSD, which does not enable the Kerberos local authentication plugin (sssd_krb5_localauth_plugin). This plugin is designed to provide local Kerberos authentication checks that prevent unauthorized impersonation. Without it, an attacker who already has the ability to modify specific AD attributes—such as userPrincipalName or samAccountName—can exploit this flaw to impersonate privileged users on domain-joined Linux hosts. This impersonation can lead to unauthorized access and privilege escalation, compromising confidentiality, integrity, and availability of affected systems. The vulnerability is remotely exploitable over the network (AV:N), requires low complexity (AC:L), but does require some privileges (PR:L) to modify AD attributes. No user interaction is needed (UI:N), and the impact is high across confidentiality, integrity, and availability (C:H/I:H/A:H). Although no known exploits are reported in the wild yet, the high CVSS score of 8.8 reflects the serious risk posed by this vulnerability. The flaw highlights the importance of secure default configurations in authentication services and the risks of delegated permissions in Active Directory environments.

For European organizations, this vulnerability poses a significant risk especially for enterprises and government agencies that rely on Red Hat Enterprise Linux 10 systems integrated with Active Directory for centralized authentication and identity management. Successful exploitation could allow attackers to impersonate privileged users, leading to unauthorized access to sensitive data, disruption of critical services, and potential lateral movement within networks. This could compromise confidential information, disrupt business operations, and damage organizational reputation. The impact is particularly severe in sectors with stringent data protection requirements such as finance, healthcare, and public administration. Additionally, organizations with hybrid Windows-Linux environments are more exposed due to the reliance on AD for authentication. The vulnerability also raises concerns about insider threats or attackers who have already gained limited access to AD attributes, as they could escalate privileges on Linux hosts without detection.

To mitigate this vulnerability, organizations should immediately review and adjust their SSSD configurations to enable the Kerberos local authentication plugin (sssd_krb5_localauth_plugin). This change enforces local Kerberos authentication checks that prevent impersonation attacks. Additionally, organizations must audit and restrict permissions in Active Directory to limit who can modify sensitive attributes like userPrincipalName and samAccountName, reducing the risk of privilege escalation. Monitoring and alerting on changes to these AD attributes should be implemented to detect suspicious activity promptly. Applying security updates and patches from Red Hat as soon as they become available is critical. Organizations should also conduct thorough security assessments of their domain-joined Linux hosts to identify any signs of compromise. Finally, implementing multi-factor authentication (MFA) for administrative accounts and enforcing the principle of least privilege across AD and Linux systems will further reduce attack surface.