CVE-2026-43112 is an out-of-bounds read vulnerability in the Linux kernel's CIFS client, specifically in the cifs_sanitize_prepath function. When called with an empty string or a string containing only delimiters, the function attempts to read memory before the start of the buffer, causing an out-of-bounds read. This flaw was identified through manual audit and verified with AddressSanitizer. The vulnerability can lead to a system crash and denial of service. Red Hat has issued a security advisory and released patches for affected Red Hat Enterprise Linux versions, including Real Time and Extended Life Cycle variants. The fix adds an early exit after stripping delimiters to prevent the out-of-bounds read.

The vulnerability can cause a system crash leading to denial of service by triggering an out-of-bounds read in kernel memory. Confidentiality impact is high as out-of-bounds reads may expose sensitive memory contents, but integrity impact is none. The vulnerability can be triggered remotely without authentication and requires user interaction. There are no known exploits in the wild at this time. The CVSS v3.1 base score is 8.8 (High).

A vendor-provided official fix is available from Red Hat. Users should apply the kernel-rt security update as described in Red Hat Advisory RHSA-2026:36365 and reboot the system to activate the patch. No additional mitigations are required beyond applying the official update.