SB20260626135 - Use-after-free in Linux kernel smb server
Published: June 26, 2026
Security Bulletin ID
SB20260626135
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Use-after-free (CVE-ID: CVE-2026-53198)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 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/E:U/U:Green
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to a use-after-free in smb2_cancel in ksmbd when handling a second SMB2_CANCEL for the same AsyncId after cancellation of a deferred byte-range lock. A remote user can send specially crafted SMB2_CANCEL requests to cause a denial of service.
Exploitation requires authentication to the SMB service and involves a deferred SMB2_LOCK request that blocks.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/stable/c/0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd
- https://git.kernel.org/stable/c/14d2eee0193ac3cd1bf3d014373449f0b8d35d6d
- https://git.kernel.org/stable/c/2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694
- https://git.kernel.org/stable/c/89ae9df09d2c1fb4a4eb495c113a7ce1dca34147
- https://git.kernel.org/stable/c/b7063c7426ea5a4d15e01b60538718765392f49d
- https://git.kernel.org/stable/c/f580d27e8928828693df44ba2db0fffdbe11dfea