CVE-2023-54046: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54046 is a use-after-free vulnerability in the Linux kernel's crypto: essiv subsystem, caused by incorrect handling of the EBUSY return value. The essiv layer only handled EINPROGRESS as a special case, meaning that when a caller specifies MAY_BACKLOG and the request is backlogged (returning EBUSY), the associated request data is incorrectly freed, leading to a use-after-free condition. The vulnerability was published on December 24, 2025, and affects Linux kernel versions starting from commit be1eb7f78aa8fbe34779c56c266ccd0364604e71 across multiple stable branches. Fixed versions include 5.4.235, 5.10.173, 5.15.99, 6.1.16, 6.2.3, and 6.3. No CVSS score has been officially assigned at this time (Feedly, EUVD).

The root cause is a use-after-free (CWE-416) in the essiv crypto template within the Linux kernel. The essiv wrapper only treated EINPROGRESS as a non-error return that should not trigger request data cleanup; however, when the underlying crypto hardware queue is full and MAY_BACKLOG is set by the caller, the crypto layer returns EBUSY to indicate the request has been queued. Because essiv did not account for EBUSY, it freed the request-associated memory prematurely, while the hardware continued to reference it asynchronously. The fix ensures EBUSY is treated identically to EINPROGRESS, preventing premature deallocation of backlogged request data (Feedly, EUVD).

Successful exploitation of this use-after-free vulnerability could allow a local attacker or a process with access to the crypto subsystem to corrupt kernel memory, potentially leading to privilege escalation, kernel crashes (denial of service), or arbitrary code execution in kernel context. The vulnerability is confined to systems using the essiv crypto template with hardware-backed crypto accelerators that support request backlogging. Data confidentiality and system integrity may both be at risk if kernel memory corruption is leveraged effectively (Feedly).

Apply the upstream kernel patches that correct the EBUSY handling in the essiv crypto template. Fixed versions are available in the following stable kernel releases: 5.4.235, 5.10.173, 5.15.99, 6.1.16, 6.2.3, and 6.3. Administrators should update to a patched kernel version as soon as possible. As a temporary workaround, disabling use of the essiv crypto template or avoiding hardware crypto accelerators with backlogging on affected systems may reduce exposure (EUVD, Feedly).