CVE-2025-3576 identifies a cryptographic vulnerability in the MIT Kerberos implementation on Red Hat Enterprise Linux 10, specifically related to the use of RC4-HMAC-MD5 for GSSAPI-protected messages. The core issue stems from the inherent weaknesses in the MD5 hashing algorithm, which is susceptible to collision attacks. When RC4 is preferred as the encryption type, the MD5 checksum used to verify message integrity can be forged by an attacker exploiting these collisions. This allows an adversary to spoof GSSAPI messages, effectively tampering with the integrity of communications without detection. The vulnerability does not affect confidentiality or availability directly but compromises message integrity, which can lead to unauthorized command execution or privilege escalation in Kerberos-authenticated sessions. The CVSS 3.1 score of 5.9 reflects a medium severity, considering the network attack vector, high attack complexity, and no requirement for privileges or user interaction. No known exploits have been reported in the wild, but the vulnerability highlights the risks of relying on deprecated cryptographic algorithms like RC4 and MD5. The vulnerability is specific to Red Hat Enterprise Linux 10, which uses the MIT Kerberos implementation, and affects all versions currently identified. The recommended security posture is to disable RC4-HMAC-MD5 preference and migrate to stronger encryption types such as AES-based algorithms in Kerberos configurations.

For European organizations, this vulnerability poses a risk to the integrity of Kerberos-authenticated communications, particularly in environments where legacy encryption preferences still allow RC4-HMAC-MD5 usage. Compromised message integrity can lead to unauthorized message tampering, potentially enabling attackers to impersonate legitimate users or escalate privileges within enterprise networks. This can affect critical services relying on Kerberos for authentication, including single sign-on systems, internal applications, and secure communications. The impact is heightened in sectors with stringent security requirements such as finance, government, and critical infrastructure. Although the vulnerability does not directly affect confidentiality or availability, the ability to forge integrity codes undermines trust in authentication mechanisms and can facilitate further attacks. European organizations using Red Hat Enterprise Linux 10 in their infrastructure should be particularly vigilant, as this is the affected product. The absence of known exploits reduces immediate risk but does not eliminate the need for proactive mitigation.

1. Immediately audit Kerberos configurations on Red Hat Enterprise Linux 10 systems to identify if RC4-HMAC-MD5 is enabled or preferred. 2. Reconfigure Kerberos to disable RC4-HMAC-MD5 and prioritize stronger encryption algorithms such as AES256-CTS-HMAC-SHA1-96 or AES128-CTS-HMAC-SHA1-96. 3. Monitor authentication logs for unusual GSSAPI message patterns that could indicate tampering attempts. 4. Apply any vendor patches or updates as soon as they become available from Red Hat addressing this vulnerability. 5. Educate system administrators about the risks of legacy cryptographic algorithms and enforce cryptographic policy updates across the enterprise. 6. For environments where legacy support is unavoidable, implement network segmentation and additional monitoring to limit exposure. 7. Conduct penetration testing focused on Kerberos authentication flows to verify the effectiveness of mitigations. 8. Coordinate with identity and access management teams to ensure that all Kerberos clients and servers comply with updated cryptographic standards.