CVE-2023-54319: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54319 is a NULL pointer dereference vulnerability in the Linux kernel's pinctrl: at91-pio4 driver, caused by a missing return value check on devm_kasprintf(). When memory allocation fails, devm_kasprintf() returns NULL, and the unchecked pointer can lead to a kernel crash or undefined behavior. The vulnerability was published on December 30, 2025, and affects multiple stable Linux kernel branches. The CVSS base score is not yet formally assigned (estimated Medium severity by Feedly), and the EPSS score is approximately 0.044% (Feedly).

The root cause is a missing NULL check after calling devm_kasprintf() in the pinctrl/at91-pio4 driver (CWE-476: NULL Pointer Dereference). devm_kasprintf() dynamically allocates and formats a string; if the allocation fails (e.g., under memory pressure), it returns NULL. Without validating the return value, subsequent use of the pointer can trigger a kernel NULL pointer dereference. The fix was identified using the Coccinelle static analysis tool (kmerr.cocci script) and depends on two prerequisite commits: 1c4e5c470a56 ("pinctrl: at91: use devm_kasprintf() to avoid potential leaks") and 5a8f9cf269e8 ("pinctrl: at91-pio4: use proper format specifier for unsigned int") (Feedly, Kernel Patch).

Successful triggering of this vulnerability can cause a kernel NULL pointer dereference, leading to a system crash (denial of service). Because the flaw resides in a kernel driver, exploitation could affect system availability on devices using the Microchip AT91/SAM-family pin controller. The vulnerability is limited to local or hardware-level triggering scenarios (e.g., during driver initialization under low-memory conditions), and there is no known path to privilege escalation or data exfiltration (Feedly).

Patches have been backported to multiple stable Linux kernel branches. Fixed versions include 4.14.322, 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.39, 6.3.13, 6.4.4, and 6.5. Users should update to the appropriate patched stable kernel release for their branch. No configuration-based workaround is available; upgrading the kernel is the recommended remediation (Feedly, Kernel Patch).