SB20260912148 - Use-after-free in Linux kernel smb client

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-89641)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 0 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to trigger a use-after-free.

The vulnerability exists due to use-after-free in the CIFS client's cifs_file_set_size() function when falling back to path-based file-size operations after a failed handle-based set_file_size() RPC. A local user can cause the fallback to reuse a freed tcon to trigger a use-after-free.

Exploitation requires a tlink to be removed during reconnection or session teardown and its last reference to be released.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/4bea15d9c7683218f57b8c1f5f0aa75cab76af8d
• https://git.kernel.org/stable/c/4f18c9e7ee464aaae5cd9fccdb943b3fcb4655d4
• https://git.kernel.org/stable/c/b96db32fed8dfb2478d7c208f89bf383beed1535