Use-after-free in Linux kernel - CVE-2026-89555

Vulnerability identifier: #VU149245

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-2026-89555

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.

The vulnerability exists due to use-after-free in mpls_multipath_hash when processing MPLS packets with inner IP headers in non-linear data and insufficient tailroom in the linear head. A remote attacker can send a legal Geneve packet through a bareudp/MPLS multipath setup to trigger a use-after-free.

The IPv6 processing path can perform a second pull for the larger header.

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.

Linux kernel - update to 7.0 rc3
kernel - update to 5.10.0-335.0.0.236
bpftool - update to 5.10.0-335.0.0.236
bpftool-debuginfo - update to 5.10.0-335.0.0.236
kernel-debuginfo - update to 5.10.0-335.0.0.236
kernel-debugsource - update to 5.10.0-335.0.0.236
kernel-devel - update to 5.10.0-335.0.0.236
kernel-headers - update to 5.10.0-335.0.0.236
kernel-source - update to 5.10.0-335.0.0.236
kernel-tools - update to 5.10.0-335.0.0.236
kernel-tools-debuginfo - update to 5.10.0-335.0.0.236
kernel-tools-devel - update to 5.10.0-335.0.0.236
perf - update to 5.10.0-335.0.0.236
perf-debuginfo - update to 5.10.0-335.0.0.236
python3-perf - update to 5.10.0-335.0.0.236
python3-perf-debuginfo - update to 5.10.0-335.0.0.236

• https://git.kernel.org/stable/c/29e63b8d9fc150cc191b1c6eb7e16e1247e1b650
• https://git.kernel.org/stable/c/49d38c1b4390412f8950d33dfaee0ccbd17beb81
• https://git.kernel.org/stable/c/d82b90a38c2ca8a0694428eab0e9551c23f2447d
• https://git.kernel.org/stable/c/fed638a248116b8a249bd4202d28e5934bdc65ad

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