CVE-2026-64597

A flaw was found in the Linux kernel's Server Message Block (SMB) client. A vulnerability exists in the SMB2_close() replay mechanism where a response buffer can be freed twice. This double-free condition can lead to memory corruption, potentially resulting in a denial of service or the execution of arbitrary code. Exploitation requires the victim system to connect to a malicious or compromised SMB server.

This flaw is rated as Important severity because kernel-space memory corruption can result in a system crash or potential arbitrary code execution, though it requires communicating with a compromised or malicious endpoint. Under standard Red Hat Enterprise Linux deployments, the SMB client is not active by default and requires explicit mounting of a remote file share. Consequently, systems that do not interact with untrusted SMB servers operate with significantly reduced risk.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

If SMB/CIFS client functionality is not required, the 'cifs' kernel module can be blocklisted to prevent it from loading. Systems that do not mount SMB/CIFS shares are not affected. For systems that require SMB client access, ensure connections are only made to trusted SMB servers.