Use-after-free in Linux kernel - CVE-2026-89637

Vulnerability identifier: #VU149166

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-89637

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause memory leaks and use-after-free conditions.

The vulnerability exists due to use-after-free in the SMB client cifs_check_trans2() function when processing a malformed secondary TRANSACT2 response. A remote attacker can send a malformed secondary TRANSACT2 response to cause memory leaks and use-after-free conditions.

Exploitation requires that a valid primary TRANSACT2 response has already been received.

Linux kernel
openEuler
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo

Install security update from vendor's repository.

linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17
bpftool - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
python3-perf-debuginfo - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
python3-perf - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
perf-debuginfo - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
perf - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-tools-devel - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-tools-debuginfo - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-tools - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-source - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-headers - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-devel - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-debugsource - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
kernel-debuginfo - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165
bpftool-debuginfo - addressed in versions 5.10.0-334.0.0.235, 6.6.0-145.1.28.165

• https://git.kernel.org/stable/c/5e6533a683f6a851158d9f33fb4ea8f4f25d7f84
• https://git.kernel.org/stable/c/730d0bb19507b9e19c2fe5343109ac618e2fbce5
• https://git.kernel.org/stable/c/9eed72e9534b10a6d9f8f5146feff3db53aebdba

• Use-after-free in Linux kernel smb client
• openEuler 22.03 LTS SP4 update for kernel
• openEuler 24.03 LTS SP1 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more