CVE-2023-53786: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53786 is a NULL pointer dereference vulnerability in the Linux kernel's dm flakey (device mapper flakey) target that can cause a kernel crash. The flaw is triggered when an invalid table line is passed to dmsetup create flakey with the corrupt_bio_byte option and an insufficient number of arguments, causing arg_name to be NULL when it is subsequently dereferenced. It affects the Linux kernel across multiple stable branches and was publicly disclosed on December 9, 2025. The CVSS estimate is Medium severity, with an EPSS score of approximately 0.033% (Feedly, VulDB).

The root cause is a missing NULL check in the dm flakey target's table parsing logic (CWE-476: NULL Pointer Dereference). When dmsetup create flakey is invoked with a malformed table line — specifically, the corrupt_bio_byte feature flag followed by an insufficient number of arguments — the kernel iterates over optional argument names and dereferences arg_name without first verifying it is non-NULL. The fix adds a guard condition to check that arg_name is non-NULL before performing string comparison. Exploitation requires local access and the ability to invoke dmsetup with a crafted table string, typically requiring elevated privileges (e.g., CAP_SYS_ADMIN) (Feedly, Kernel Git).

Successful exploitation causes a kernel NULL pointer dereference, resulting in a system crash (kernel panic) and denial of service. Because this is a local vulnerability requiring privileged access to the device mapper subsystem, there is no direct path to remote code execution or data exfiltration. The primary impact is availability — an attacker or misconfigured script with sufficient privileges could crash the affected system, disrupting all services running on it (Feedly).

The vulnerability is fixed in the following stable Linux kernel versions: 4.14.315, 4.19.283, 5.4.243, 5.10.180, 5.15.111, 6.1.28, 6.2.15, 6.3.2, and 6.4. Administrators should update to a patched kernel version for their respective stable branch. As a workaround, restricting access to dmsetup and the device mapper subsystem (e.g., limiting CAP_SYS_ADMIN capabilities) reduces exposure until patching is possible (Feedly, Kernel Git).