Linux Kernel Vulnerability: CVE-2026-74741 - NULL Pointer Dereference in Non-MSI-X Interrupt Enabling

Executive Summary

A vulnerability, identified as CVE-2026-74741, has been discovered in the Linux kernel's ngbe driver. This vulnerability leads to a NULL pointer dereference in non-MSI-X interrupt enabling and has a CVSS score of 7.5, indicating a high severity level. The vulnerability affects certain versions of the Linux kernel, specifically those prior to specific commits and version 6.16.

Technical Analysis

The vulnerability is classified as a NULL pointer dereference issue. It occurs in non-MSI-X mode (such as legacy INTx or single MSI) where `wx->msix_entry` is not allocated or initialized. When `NGBE_INTR_MISC(wx)` is called, it dereferences `wx->msix_entry->entry`, leading to a NULL pointer dereference crash. The root cause of this issue is the lack of explicit checking of `pdev->msix_enabled` to determine the correct vector index.

How It Gets Exploited

An attacker could exploit this vulnerability by triggering the `NGBE_INTR_MISC(wx)` function in a non-MSI-X mode. This would involve sending a specific type of network request or packet that activates the interrupt handling in a way that dereferences the NULL pointer. The attacker would need to have a way to interact with the network interface, potentially through a network connection. Upon triggering the vulnerability, the system could crash, leading to a denial of service (DoS).

Impact Assessment

The impact of this vulnerability is a denial of service (DoS) attack, which could lead to system crashes and instability. The CVSS score of 7.5 indicates a high severity level. Affected systems include Linux kernel versions prior to specific commits and version 6.16. The vulnerability does not allow for remote code execution or data exfiltration but can significantly impact system availability.

Recommended Actions

To mitigate this vulnerability, it is recommended to update the Linux kernel to a version that includes the fix. Specifically, apply updates to ensure the kernel version is beyond the affected commits: - Update Linux kernel to version 0ab482b2195edc000262f0eae1cdcb416b8f335d or later. - Update Linux kernel to version 5f3a13e0bb5ebcc1ca2dfda42ea40b9f3c2be6ea or later. - For version 6.16 and later, ensure the system is updated to the latest patch level. Additionally, implement network segmentation and access controls to limit the attack surface.

Sources

- National Vulnerability Database (NVD): CVE-2026-74741