Use-after-free in Linux kernel - CVE-2026-89655

Vulnerability identifier: #VU149153

CSH Severity: Low

CVSS v4: 0 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-89655

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to trigger a use-after-free condition.

The vulnerability exists due to use-after-free in __kick_flushing_caps() when processing FLUSH_ACK messages during cap flushing. A remote attacker can send a FLUSH_ACK message during cap flushing to trigger a use-after-free condition.

Exploitation requires the FLUSH_ACK to be processed after i_ceph_lock is released and before list iteration resumes.

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/2701431aa3cc8b23efe6890182e7b04f5e76fab5
• https://git.kernel.org/stable/c/2dba24dcd5050be4b7b119e6f0b01f62203b5d26
• https://git.kernel.org/stable/c/7af4c4f01305b0935adf6d4301b1ec407025485d
• https://git.kernel.org/stable/c/fe46746087b5b9c5bb2d022df6c7819218494ced

• Use-after-free in Linux kernel ceph
• openEuler 22.03 LTS SP4 update for kernel