CVE-2026-74401

A flaw was found in the Linux kernel's Distributed Lock Manager (DLM) subsystem. Under specific high-load network conditions, the system could incorrectly order internal messages. This issue can lead to memory corruption, which might allow a local attacker to cause the system to crash (denial of service) or potentially gain elevated privileges.

A race in DLM midcomms can assign mh seq after the message handle is already inserted into node send_queue, so the queue order may not match the sequence order expected by dlm_receive_ack. Under heavy DLM request load this can break acknowledgement processing and lead to refcounting errors and use-after-free of send buffers. For the CVSS the PR:L is used because reliable triggering normally requires a local user or service that can generate DLM workload on a cluster node, or access as a cluster adjacent peer, but not full administrative privileges on the victim. The issue is network adjacent rather than Internet remote because DLM is normally used on trusted cluster networks.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.