Out-of-bounds write in Linux kernel - CVE-2026-89633

Vulnerability identifier: #VU149179

CSH Severity: Medium

CVSS v4: 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]

CVE-ID: CVE-2026-89633

CWE-ID: CWE-787

Exploitation vector: Remote access

Exploit availability: No public exploit available

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.

Linux kernel
openEuler
kernel
bpftool
bpftool-debuginfo
kernel-debuginfo
kernel-debugsource
kernel-devel
kernel-headers
kernel-source
kernel-tools
kernel-tools-debuginfo
kernel-tools-devel
perf
perf-debuginfo
python3-perf
python3-perf-debuginfo

Install security update from vendor's repository.

kernel - update to 5.10.0-334.0.0.235
bpftool - update to 5.10.0-334.0.0.235
bpftool-debuginfo - update to 5.10.0-334.0.0.235
kernel-debuginfo - update to 5.10.0-334.0.0.235
kernel-debugsource - update to 5.10.0-334.0.0.235
kernel-devel - update to 5.10.0-334.0.0.235
kernel-headers - update to 5.10.0-334.0.0.235
kernel-source - update to 5.10.0-334.0.0.235
kernel-tools - update to 5.10.0-334.0.0.235
kernel-tools-debuginfo - update to 5.10.0-334.0.0.235
kernel-tools-devel - update to 5.10.0-334.0.0.235
perf - update to 5.10.0-334.0.0.235
perf-debuginfo - update to 5.10.0-334.0.0.235
python3-perf - update to 5.10.0-334.0.0.235
python3-perf-debuginfo - update to 5.10.0-334.0.0.235

• https://git.kernel.org/stable/c/033bc80019f07d158630df4e69b19a49010f54f1
• https://git.kernel.org/stable/c/6343c1da561962688f203362d80d6a3bfa39fa1b
• https://git.kernel.org/stable/c/672cf86aa6aa0fb4012ce4c3b3498df42ad67a4e

• Out-of-bounds write in Linux kernel smb client
• openEuler 22.03 LTS SP4 update for kernel