CVE-2025-39979

A use-after-free flaw was discovered in the Linux kernel’s mlx5 (Net/MLX5) subsystem: within the function mlx5_cmd_hws_delete_fte() the HWS action reference count and mutex for a local flow counter were not initialized, meaning the flow-counter structure could already be freed while deleting the rule. This may lead to memory corruption or kernel instability.

This vulnerability is rated as Moderate severity because exploitation requires systems configured with Mellanox ConnectX hardware utilizing hardware steering, restricting the attack surface to environments with specific network adapters. A local user with permissions to manipulate network flow rules or InfiniBand user verbs can trigger a use-after-free condition during flow table cleanup, potentially resulting in kernel memory corruption or a system crash. Systems lacking Mellanox network interfaces or where hardware flow steering is not actively engaged are not exposed to this issue.

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.