CVE-2023-53824: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53824 is a data race vulnerability in the Linux kernel's netlink subsystem, specifically involving lockless accesses to the nlk->max_recvmsg_len field. The flaw was reported by syzbot (Google's kernel fuzzer) and disclosed on December 9, 2025. It affects the Linux kernel's net/netlink/af_netlink.c component, where netlink_recvmsg() can be executed concurrently without proper synchronization, and netlink_dump() also lacks adequate protection. Feedly estimates this as a Medium severity vulnerability with an EPSS score of 0.00018 (Feedly).

The root cause is a concurrent read/write data race (CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization) on the nlk->max_recvmsg_len field in the Linux kernel's netlink socket implementation. As reported by KCSAN (Kernel Concurrency Sanitizer), two tasks running on separate CPUs can simultaneously read and write to the same memory address (0xffff888141840b38) in netlink_recvmsg() at net/netlink/af_netlink.c lines 1988–1989, without any locking primitives protecting the access. The fix involves annotating these accesses appropriately (e.g., using READ_ONCE/WRITE_ONCE or equivalent atomic operations) to prevent undefined behavior from unsynchronized concurrent access. Patches are available in the stable kernel tree across multiple commits (Feedly).

The data race can lead to undefined behavior in the kernel's netlink message receiving path, potentially causing memory corruption, incorrect buffer sizing, or kernel instability. In practice, the most likely outcomes are system crashes (denial of service) or subtle memory safety issues that could, under specific conditions, be leveraged for privilege escalation by a local attacker. The impact is primarily on availability and integrity of the kernel's netlink communication subsystem, which is used broadly by system utilities and network management tools (Feedly).

The fix has been applied to the Linux kernel stable tree via multiple commits (e.g., 05c9e3fc93b0, 7cff4103be7c, a1865f2e7d10, e3bcf2a77060, fc4ba13013dd). Users should update to a patched kernel version that includes these commits. Linux distribution maintainers (e.g., Red Hat, Ubuntu, Debian, SUSE) are expected to backport the fix into their respective stable releases. No configuration-based workaround is available; kernel update is the only remediation (Feedly, Tenable).