CVE-2023-54264: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54264 is a null pointer dereference vulnerability in the Linux kernel's fs/sysv filesystem subsystem. The flaw occurs when sb_getblk(inode->i_sb, parent) returns a null pointer and a lock is subsequently taken on that null pointer, triggering a null-ptr-deref bug. The vulnerability was published on December 30, 2025, and affects multiple stable Linux kernel branches from 4.14 through 6.4. Feedly estimates the severity as Medium, with an EPSS score of 0.000240 (Feedly).

The root cause is a missing null pointer check in the fs/sysv filesystem driver (CWE-476: NULL Pointer Dereference). When sb_getblk() fails to allocate or retrieve a buffer head and returns NULL, the code proceeds to acquire a lock on the null pointer without first validating the return value. This is a local kernel vulnerability requiring an attacker to trigger specific filesystem operations on a SysV filesystem. The fix involves adding a null check after the sb_getblk() call before any lock or dereference operations are performed (Feedly, Kernel Git).

Successful exploitation of this vulnerability can cause a kernel panic or system crash (denial of service) on affected Linux systems. Because the null pointer dereference occurs in kernel space, it results in an oops or BUG condition that may render the system unavailable. There is no evidence of confidentiality or integrity impact beyond availability loss; lateral movement or data exfiltration are not expected outcomes of this vulnerability (Feedly).

The Linux kernel project has released patches across multiple stable branches. Fixed versions include: 4.14.322, 4.19.291, 5.4.253, 5.10.190, 5.15.126, 6.1.45, 6.4.10, and 6.5. Administrators should update their Linux kernel to one of these patched versions. The specific fix commits are available in the kernel stable tree (Feedly, Kernel Git).

Patched stable commits:

• 4.14.x: ea2b62f305893992156a798f665847e0663c9f41
• 4.19.x: e976988bc245ec3768cc0f76bed7d05488a7dd0f
• 5.4.x: baa60c66a310c50785289b0ede6fdce8ec3219c7
• 5.10.x: 0a44ceba77c3267f8505dda102a59367dc24caee
• 5.15.x: 7f740bc696d4617f8ee44565e8ac0d36278a1e91
• 6.1.x: afd9a31b5aa4b3747f382d44a7b03b7b5d0b7635
• 6.4.x: 1416eebaad80bdc85ad9f97f27242011b031e2a9