Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: smb: client: fix change notify replay double-free A response-bearing attempt can… (CVE-2026-64384)

CVE-2026-64384 is a double-free vulnerability in the SMB client code of the Linux kernel. When a response-bearing SMB operation returns a replayable error and frees its response buffer, a failure in SMB2_notify_init() before the next send causes the cleanup routine to free the previously freed buffer again due to stale bookkeeping. This double-free can lead to memory corruption and potentially system compromise. The fix involves resetting the response bookkeeping state before each SMB attempt to prevent reuse of stale pointers. The vulnerability affects multiple Linux kernel builds under the linux-hwe-edge product line prior to version 7.0.0-31.31 and related versions. Ubuntu has released official patches addressing this issue as part of their September 2026 security notices.

Successful exploitation of this double-free vulnerability could lead to memory corruption, which may allow an attacker to cause a denial of service or potentially escalate privileges on the affected system. The CVSS v3.1 score of 9.8 indicates critical impact on confidentiality, integrity, and availability. However, there are no known exploits in the wild at this time.

An official patch is available and should be applied by updating the Linux kernel to versions 7.0.0-31.31 or later as provided by Ubuntu security updates (e.g., USN-8726-1). After updating, a system reboot is required. Due to an ABI change, third-party kernel modules must be recompiled and reinstalled. Users should follow the vendor's update instructions carefully to ensure full remediation.