CVE-2023-53853: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53853 is a data race vulnerability in the Linux kernel's netlink subsystem, specifically involving unsynchronized accesses to the nlk->cb_running field. Both netlink_recvmsg() and netlink_native_seq_show() read this field without proper synchronization primitives, while netlink_dump() and __netlink_dump_start() write to it concurrently. The vulnerability was published on December 9, 2025, and affects the Linux kernel across multiple stable branches. It carries an estimated CVSS severity of Medium, with an EPSS score of 0.024% (Feedly).

The root cause is a data race (CWE-362: Concurrent Execution Using Shared Resource with Improper Synchronization) in net/netlink/af_netlink.c. The nlk->cb_running boolean field is written in __netlink_dump_start() (at offset +0x3af/0x4d0) and read locklessly in netlink_recvmsg() and netlink_native_seq_show(), creating a race condition detectable by KCSAN (Kernel Concurrency Sanitizer). The fix annotates the writes with WRITE_ONCE() and the reads with READ_ONCE() to ensure proper memory ordering without requiring a full lock, as reported by syzbot (Feedly). Patches are available in the Linux stable tree at multiple commit references including 1d5c8b01, 02e7afd6, 840a6474, a115dadf, and a939d149.

The data race can lead to undefined behavior in the kernel's netlink dump path, potentially causing incorrect reads of the cb_running state, which could result in logic errors, kernel instability, or information disclosure from kernel memory. In practice, the impact is primarily a reliability and availability concern — a racing condition could cause the kernel to make incorrect decisions about ongoing netlink dump operations, potentially leading to use-after-free scenarios or kernel panics under specific timing conditions. The vulnerability is confined to the netlink subsystem and does not directly enable remote code execution or privilege escalation in typical exploitation scenarios (Feedly).

The fix has been applied to multiple Linux stable kernel branches via upstream commits (1d5c8b01f1df, 02e7afd659a4, 840a647499b0, a115dadf8995, a939d14919b7). Users should update to a patched kernel version that includes these commits. Linux distribution vendors (e.g., Red Hat, Ubuntu, SUSE) are expected to backport the fix into their respective kernel packages; administrators should apply available kernel updates from their distribution. Detection is available via Nessus plugin 298924 and Qualys detection ID 677618 (Feedly).