CVE-2025-39973

Vulnerability

Overview

CVE-2025-39973 describes a missing validation in the Intel i40e network driver for the Linux kernel. The ring_len parameter provided by a virtual function (VF) is assigned directly to the hardware memory context (HMC) without any bounds checking. This can allow a malicious or compromised VF to specify excessive queue lengths, potentially leading to memory corruption or denial of service.

Impact and

Exploitation

An attacker with access to a VF on a system using the i40e driver can set ring_len to values beyond the hardware maximum (8K-32 descriptors) or violate alignment constraints (Tx rings must be multiple of 8, Rx rings multiple of 32). The unchecked assignment to HMC could cause the hardware to access out-of-bounds memory, resulting in system instability or privilege escalation.

Mitigation

The fix introduces upper boundary checks and alignment validation for both Tx and Rx queue lengths. The kernel community has backported the patch to multiple stable branches, as seen in commits [1], [2], [3], and [4]. Users should update to the latest stable kernel version to mitigate the vulnerability.