The Linux kernel's platform/x86 hp-bioscfg module had a heap out-of-bounds read vulnerability (CVE-2026-81013) caused by improper validation of password input length. Specifically, validate_password_input() computed the length of the input buffer and then accessed buf[length - 1] to strip a trailing newline without verifying that length was greater than zero. Writing an empty string (just a newline) resulted in reading one byte before the allocated heap buffer, confirmed by KASAN diagnostics. Although this out-of-bounds read does not cause a crash and execution continues, it constitutes an information leak and memory safety violation. The patch fixes this by adding a check to ensure length is nonzero before accessing buf[length - 1].

This vulnerability allows a one-byte out-of-bounds read from heap memory when an empty password string is written. While it does not cause a crash or denial of service, it represents a memory safety flaw that could potentially leak information from adjacent memory. No known exploits in the wild have been reported. The impact is limited to information disclosure via an invalid memory read.

A fix has been implemented in the Linux kernel to address this vulnerability by adding a check to ensure the buffer length is nonzero before accessing its last character. Users and administrators should apply the official kernel update containing this patch to remediate the issue. No additional mitigation is required beyond applying the fixed kernel version.