CVE-2023-54062: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54062 is a memory management vulnerability in the Linux kernel's ext4 filesystem subsystem, specifically in the ext4_xattr_move_to_block() function. The flaw involves invalid free tracking when moving extended attribute (xattr) values to an external block, potentially resulting in calling kvfree() on a pointer not allocated by kvmalloc(), or a memory leak. It affects the Linux kernel across multiple stable branches and was publicly disclosed on December 24, 2025. No CVSS score has been assigned at this time, and the ENISA base score is listed as 0.0 (Feedly, ENISA EUVD).

The root cause is improper memory management (CWE-763: Release of Invalid Pointer or Reference) in ext4_xattr_move_to_block(). When an extended attribute value is stored in an external inode, it may be allocated via kvmalloc(); however, after the xattr entry is removed from its original location, the pointer entry->e_value_inum used to determine whether to call kvfree() is no longer valid. This stale pointer dereference can lead to either a double-free/invalid-free condition or a memory leak, depending on the state of the pointer at the time of the check. The fix stores the free-eligibility decision in a separate boolean variable before the entry is invalidated (Feedly, Kernel Git).

Exploitation of this vulnerability could result in kernel memory corruption due to an invalid kvfree() call on a non-kvmalloc()-allocated pointer, potentially leading to a kernel panic (denial of service) or, in more severe scenarios, exploitation of the corrupted heap state for privilege escalation. Alternatively, the memory leak path could degrade system stability over time. The vulnerability is local in nature and requires the ability to manipulate ext4 extended attributes, limiting its scope to users or processes with filesystem access (Feedly).

The Linux kernel maintainers have released patches across multiple stable branches. Fixed versions include: 4.14.315, 4.19.283, 5.4.243, 5.10.180, 5.15.112, 6.1.29, 6.2.16, 6.3.3, and 6.4. Administrators should update to the appropriate patched kernel version for their distribution. No configuration-based workaround is available; upgrading the kernel is the recommended remediation (Feedly, ENISA EUVD).