CVE-2023-54105: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54105 is a missing input validation vulnerability in the Linux kernel's CAN ISO-TP (isotp) socket implementation, specifically in the isotp_bind() function. The flaw allows a local user to call bind() on an isotp socket using a non-AF_CAN address family (e.g., AF_XDP, value 0x2C) without receiving an error, when the correct family should be AF_CAN (0x1D). The issue was discovered via Syzbot fuzzing and disclosed on December 24, 2025. It affects multiple stable Linux kernel branches prior to patched versions including 5.10.200, 5.15.138, 6.1.16, 6.2.3, and 6.3. The CVSS base score is estimated as Medium (no official score assigned at time of publication) (Feedly, EUVD).

The root cause is a missing address family validation check in the isotp_bind() function of the Linux kernel's CAN ISO-TP socket layer (CWE-20: Improper Input Validation). When a bind() syscall is made on an isotp socket, the kernel did not verify that the sa_family field of the provided sockaddr structure was set to AF_CAN (0x1D). Syzbot demonstrated the issue by crafting a bind$xdp() call with AF_XDP (0x2C) in the address family field but with a sockaddr struct of the correct size for sockaddr_can, which passed without error. The fix adds an explicit check to return an error to userspace when a non-AF_CAN family is specified. Patches are available across multiple stable kernel trees (Feedly, EUVD).

The practical security impact of this vulnerability is low, as the kernel maintainers explicitly note it has "no functional impact." The flaw results in incorrect behavior where userspace is not notified of an invalid address family being used in a bind() call on a CAN isotp socket, which could lead to subtle application-level bugs or unexpected behavior in programs relying on proper error handling. There is no known path to privilege escalation, data exfiltration, or denial of service directly from this vulnerability (Feedly).

The Linux kernel maintainers have released patches across multiple stable branches. Users should update to the following patched versions or later: Linux 5.10.200, 5.15.138, 6.1.16, 6.2.3, or 6.3. The specific fix commits are available in the kernel stable tree (e.g., c6adf659a8ba, 9427584c2f15, 2fc6f337257f, dd4faace51e4, de3c02383aa6). Distributions such as openSUSE have also tracked this issue (openSUSE bug 1256146). No configuration-based workaround is available; applying the kernel update is the recommended remediation (Feedly, EUVD).