CVE-2025-40053: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-40053 is a vulnerability discovered in the Linux kernel affecting the D-Link network driver. The vulnerability was published on October 28, 2025, and specifically impacts the handling of copy_thresh allocation in the network subsystem (NVD Database, Red Hat Security).

The vulnerability stems from improper handling of netdevallocskbipalign() failure in the D-Link driver. When the allocation fails, attempting to dereference skb->protocol could lead to a NULL pointer dereference. This vulnerability has been assigned a CVSS v3.1 score of 7.0 (High) with the vector string CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. The issue has been specifically confirmed on D-Link DGE-550T Rev-A3 hardware (NVD Database).

The vulnerability affects multiple versions of Red Hat Enterprise Linux, including versions 8, 9, and 10, particularly impacting their kernel and kernel-rt packages. The vulnerability could potentially lead to system crashes due to NULL pointer dereference, affecting system stability and availability (Red Hat Security).

A patch has been developed that implements proper error handling for skb allocation failures. The fix includes a fallback path that is triggered when the allocation fails, preventing the NULL pointer dereference condition (NVD Database).