CVE-2025-24528 in Kerberos 5
Summary
by MITRE • 01/16/2026
In MIT Kerberos 5 (aka krb5) before 1.22 (with incremental propagation), there is an integer overflow for a large update size to resize() in kdb_log.c. An authenticated attacker can cause an out-of-bounds write and kadmind daemon crash.
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Analysis
by VulDB Data Team • 02/17/2026
The vulnerability CVE-2025-24528 represents a critical integer overflow flaw within the MIT Kerberos 5 implementation that specifically affects versions prior to 1.22 when incremental propagation is enabled. This issue resides in the kdb_log.c source file where the resize() function fails to properly validate input parameters during update operations. The vulnerability manifests when an authenticated attacker crafts a malicious update request containing an excessively large size parameter that triggers integer overflow conditions during memory allocation operations. The flaw falls under CWE-190 which specifically addresses integer overflow conditions that can lead to memory corruption and arbitrary code execution. This vulnerability is particularly concerning within kerberos environments where kadmind daemon services are critical for authentication and authorization operations across distributed systems.
The technical exploitation of this vulnerability occurs through a carefully constructed update request that leverages the incremental propagation feature of kerberos. When the resize() function processes an update with an oversized parameter, the integer overflow causes the memory allocation routine to compute an incorrect buffer size, resulting in an out-of-bounds write condition. This memory corruption can be leveraged by an authenticated attacker to overwrite adjacent memory locations, potentially leading to arbitrary code execution or service disruption. The kadmind daemon, which serves as the administration daemon for kerberos, becomes vulnerable to crashes and potential compromise when processing such malformed update requests. The vulnerability demonstrates characteristics consistent with CWE-787 which describes out-of-bounds write conditions that can result from improper bounds checking of array data structures.
The operational impact of CVE-2025-24528 extends beyond simple service disruption to potentially enable more sophisticated attacks within kerberos-based authentication infrastructures. Organizations relying on kerberos for enterprise authentication, single sign-on systems, and cross-domain authentication services face significant risk from this vulnerability. The authenticated nature of the attack means that an attacker must already possess valid credentials to exploit the flaw, but this reduces the barrier to exploitation compared to unauthenticated attacks. The vulnerability can be particularly dangerous in environments where kerberos is used for critical infrastructure authentication, as successful exploitation could lead to privilege escalation or lateral movement within the network. This vulnerability aligns with ATT&CK technique T1550.003 which covers use of kerberos for privilege escalation and lateral movement within enterprise environments.
Mitigation strategies for CVE-2025-24528 primarily focus on upgrading to MIT Kerberos 5 version 1.22 or later where the integer overflow has been addressed through proper input validation and bounds checking. Organizations should implement immediate patch management procedures to update all affected kerberos installations, particularly those running kadmind daemon services. Network segmentation and access controls should be strengthened to limit the potential impact of successful exploitation attempts, while monitoring systems should be configured to detect unusual update patterns or authentication requests that might indicate exploitation attempts. Additionally, implementing proper input validation at multiple layers of the authentication infrastructure can provide defense-in-depth against similar vulnerabilities. The fix implemented in version 1.22 includes enhanced bounds checking in the resize() function and proper integer overflow protection mechanisms that prevent malicious update requests from causing memory corruption. Security teams should also conduct thorough vulnerability assessments to identify any other instances where similar integer overflow conditions might exist within kerberos implementations or related authentication services.