SB20260720217 - Use-after-free in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-64016)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to a use-after-free in ksmbd durable reconnect handling in smb2_open() when processing a durable reconnect followed by a later error path. A remote user can trigger a durable reconnect sequence that republishes a file object and then reaches the error path to cause a denial of service.

The issue occurs when the same file object is referenced by both fp and dh_info.fp, allowing the object to be freed while its volatile-id entry remains published in the session table.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/3515503322f4819277091839eed46b695096aca5
• https://git.kernel.org/stable/c/6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3
• https://git.kernel.org/stable/c/a1a39f227c80cbf369767badc32cba2b225147d1