SB20261015119 - Out-of-bounds write in Linux kernel s390 boot
Published: October 15, 2026
Security Bulletin ID
SB20261015119
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Information disclosure
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Out-of-bounds write (CVE-ID: CVE-2026-98403)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 0 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a local user to corrupt memory.
The vulnerability exists due to an out-of-bounds write in append_ipl_block_parm() in arch/s390/boot/ipl_parm.c when appending an IPL parameter to a command line that occupies all but the terminating byte of COMMAND_LINE_SIZE. A local user can supply an IPL parameter that causes the conversion helpers to write beyond the early_command_line buffer to corrupt memory.
Remediation
Install update from vendor's website.