SB20260912147 - Integer underflow in Linux kernel smb client
Published: September 12, 2026
Security Bulletin ID
SB20260912147
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Integer underflow (CVE-ID: CVE-2026-89640)
CWE-ID: CWE-191 - Integer underflow
CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to corrupt the ByteCount in a file-clone request.
The vulnerability exists due to an integer underflow in cifs_remap_file_range() when issuing a clone-to-EOF operation with a source offset beyond the end of the source file. A local user can invoke a clone-to-EOF operation with an out-of-range source offset to corrupt the ByteCount in a file-clone request.
Remediation
Install update from vendor's website.