CVE-2025-39987: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-39987 is a vulnerability discovered in the Linux kernel affecting the hi311x CAN driver. The vulnerability was disclosed on October 15, 2025, and involves a buffer overflow issue in the CAN framework logic. The vulnerability specifically affects the hi311x driver's handling of MTU settings and CAN XL frames (NVD).

The vulnerability stems from the sun4ican driver not populating its netdeviceops->ndochangemtu(), which allows an attacker to configure an invalid MTU. By using PFPACKET sockets with the ETHPCANXL protocol, an attacker can bypass CAN framework logic and inject malicious CAN XL frames. The driver misinterprets these frames as standard CAN frames, leading to a buffer overflow of up to 247 bytes in hi3110hwtx() when copying frame data (NVD).

The vulnerability allows an attacker to cause a buffer overflow condition, which could potentially lead to memory corruption and system instability. The impact is particularly severe as it affects the kernel's CAN bus implementation, which is commonly used in automotive and industrial control systems (NVD).

The fix involves populating netdeviceops->ndochangemtu() to ensure that the interface's MTU cannot be set to anything larger than CAN_MTU. This prevents the buffer overflow by addressing the root cause of the vulnerability (NVD).