CVE-2023-54170: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54170 is a Linux kernel vulnerability in the key management subsystem that causes a kernel crash (BUG_ON) when a duplicate index key is inserted into a keyring's assoc_array. The flaw is triggered during DNS queries inside the kernel via dns_query(), which can in rare race conditions create a duplicate key entry in the destination keyring's associative array. It affects the Linux kernel and was published to NVD on December 30, 2025. The EPSS score is 0.024% (low), and no CVSS score has been formally assigned at this time (Feedly).

The root cause is a logic error in the kernel's key linking code (keys subsystem) that fails to detect and handle duplicate index keys before inserting them into a keyring's assoc_array data structure (CWE-617: Reachable Assertion). When dns_query() is called concurrently or under specific timing conditions, a duplicate key can be created and linked to the keyring, eventually triggering a BUG_ON() assertion at lib/assoc_array.c:652 during the insert operation. The crash manifests as an invalid opcode exception (kernel BUG at ../lib/assoc_array.c:652!) in the context of a kernel worker thread (e.g., cifsiod/cifs_resolve_server). Fixes are available as patches to the stable kernel tree (Feedly, Kernel Git).

Successful triggering of this vulnerability results in a kernel panic (crash), causing a complete loss of availability for the affected system. The crash occurs in kernel space and cannot be recovered without a reboot, making this a denial-of-service condition. There is no evidence of confidentiality or integrity impact, as the vulnerability does not enable code execution or data exfiltration (Feedly).

There is no known public exploit code or evidence of in-the-wild exploitation for CVE-2023-54170. The vulnerability requires a rare race condition during kernel DNS resolution (e.g., via CIFS/SMB workloads), making reliable triggering difficult. The EPSS score is 0.024%, indicating a very low probability of exploitation in the near term. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (Feedly).

• Logs: Kernel logs (dmesg or /var/log/kern.log) containing kernel BUG at ../lib/assoc_array.c:652! or invalid opcode: 0000 [#1] SMP PTI.
• Process: Crash occurring in the context of kworker threads associated with cifsiod or cifs_resolve_server, indicating CIFS/SMB DNS resolution activity at time of crash.
• System: Unexpected system reboots or kernel panic events on systems performing kernel-level DNS queries, particularly in environments using CIFS/SMB mounts.

Apply the upstream kernel patches that fix the duplicate key linking logic in the keys subsystem. Patches have been committed to the stable kernel tree across multiple stable branches (commits 0a6b0ca, 00edfa6, 9aecfeb, 65bd66a, d559015). Linux distribution vendors including SUSE have issued updated kernel packages addressing this issue. Users should update to a patched kernel version provided by their distribution as soon as possible (Feedly, Linux Security).