CVE-2026-72044 is a stack buffer overflow vulnerability in the Linux kernel's ksmbd component affecting multichannel session-key copying. The vulnerability arises because the per-channel session key buffer was sized at 16 bytes, but the code copied up to 40 bytes, allowing a potential overflow of up to 24 bytes on the kernel stack. This occurs during NTLM or Kerberos authentication when a session key longer than 16 bytes is supplied. The issue was resolved by resizing the per-channel key buffer and related on-stack buffers to 40 bytes, matching the maximum allowed session key size.

This vulnerability could allow an attacker to overflow the kernel stack buffer during authentication, potentially leading to kernel memory corruption or other undefined behavior. No known exploits in the wild have been reported. The impact is considered high due to the nature of kernel stack buffer overflows, which can lead to privilege escalation or system compromise if exploited.

A fix has been implemented that resizes the per-channel session key buffer and related on-stack buffers to 40 bytes to prevent overflow. Users should apply the official Linux kernel updates that include this fix once available. Patch status is not yet confirmed from vendor advisory; check the Linux kernel security advisories for the official patch and remediation guidance.