SB20260912157 - Out-of-bounds write in Linux kernel smb client
Published: September 12, 2026
Security Bulletin ID
SB20260912157
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Out-of-bounds write (CVE-ID: CVE-2026-89633)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to cause out-of-bounds reads and writes.
The vulnerability exists due to improper input validation in coalesce_t2() when processing SMB transaction responses containing server-supplied DataOffset fields. A remote attacker can send a crafted response with malicious DataOffset values to cause out-of-bounds reads and writes.
Remediation
Install update from vendor's website.