CVE-2023-54145: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54145 is a low-severity vulnerability in the Linux kernel's BPF (Berkeley Packet Filter) verifier subsystem. The issue involves an unnecessary user-triggerable WARN_ONCE call in the verifier log that can be trivially triggered by a local user, as the verifier uses a fixed-size 1024-byte buffer that can be overflowed by user-controlled BTF names or BTF.ext source code line strings. The fix removes the spurious warning, as the code continues to function correctly (at worst truncating a single line of output). It was published on December 24, 2025, with a CVSS base score of 0.0 (Informational/None) and an EPSS score of 0.000170 (Feedly, EUVD).

The root cause is an improperly placed WARN_ONCE macro in the Linux kernel BPF verifier log path (CWE-390: Detection of Error Condition Without Action). The verifier log uses a fixed 1024-byte buffer, and two user-controlled inputs — BTF (BPF Type Format) names and BTF.ext source code line strings — can be arbitrarily sized, making it trivial for any local user to trigger the "verifier log line truncated" kernel warning. The fix, applied across multiple stable branches, simply removes the WARN_ONCE check since the truncation is a known, benign limitation of the buffer design (Feedly, Kernel Patch 6.4.7).

The practical impact of this vulnerability is minimal. A local user can cause a kernel WARN_ONCE message to be emitted in the kernel log, which may contribute to log noise or, in some configurations, trigger kernel warning handlers. There is no confidentiality, integrity, or availability impact beyond potential log pollution, and no code execution, privilege escalation, or data exposure is possible through this issue (Feedly, EUVD).

The fix has been backported to multiple Linux stable kernel branches: version 6.5, 6.4.7, and 6.1.107. Administrators should update to these patched versions or any later stable release. The relevant kernel commits are available at the official kernel stable repository for each affected branch (Kernel Patch 6.4.7, Kernel Patch 6.5, Kernel Patch 6.1.107).