CVE-2023-53832: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53832 is a null pointer dereference vulnerability in the Linux kernel's md/raid10 subsystem, specifically within the raid10_sync_request function. The flaw was introduced by commit 7e83ccbecd60 ("md/raid10: Allow skipping recovery when clean arrays are assembled") and affects Linux kernel versions from that commit onward until the respective stable-branch fixes. It was published on December 9, 2025, and has an estimated CVSS severity of Medium (Feedly, EUVD). Fixed versions include kernel 4.19.283, 5.4.243, 5.10.180, 5.15.111, 6.1.28, 6.2.15, 6.3.2, and 6.4 (Feedly).

The root cause is a null pointer dereference (CWE-476) in the raid10_sync_request function of the Linux kernel's RAID10 MD (Multiple Device) driver. The issue arises because init_resync() initializes a mempool and sets conf->have_replacement at the start of a sync operation, while close_sync() is expected to free the mempool upon completion. However, after commit 7e83ccbecd60, recovery can be skipped — causing init_resync() to be called (resetting conf->have_replacement to 0) without a corresponding close_sync() call. In a subsequent recovery cycle where a device has a replacement, r10bio->dev[i].repl_bio is not allocated because conf->have_replacement is 0, leading to a null pointer dereference when the code attempts to access it. The fix prevents init_resync() from being called when recovery is skipped (Feedly, Kernel Git).

Successful triggering of this vulnerability causes a kernel null pointer dereference, which typically results in a kernel panic (system crash), leading to a denial of service for the affected host. The vulnerability is exploitable locally by users or processes with access to RAID10 array management operations. There is no evidence of confidentiality or integrity impact; the primary consequence is availability loss due to system crash (Feedly).

Apply the upstream Linux kernel patches that fix this issue by preventing init_resync() from being called when recovery is skipped. Fixed stable kernel versions are: 4.19.283, 5.4.243, 5.10.180, 5.15.111, 6.1.28, 6.2.15, 6.3.2, and 6.4 (Feedly). Users of affected distributions should apply vendor-provided kernel updates as soon as available. No configuration-based workaround is known; upgrading to a patched kernel version is the recommended remediation.