Out-of-bounds write in Linux kernel - CVE-2026-89656

Vulnerability identifier: #VU149154

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-89656

CWE-ID: CWE-787

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to write beyond the CRUSH workspace.

The vulnerability exists due to improper validation of bucket IDs in the libceph CRUSH map decoder, crush_decode(), when processing a malformed CRUSH map containing a bucket ID that does not match its array slot. A local user can cause the kernel to process such a map and write past a permutation array into memory beyond the CRUSH workspace.

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 5.10.0-335.0.0.236
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/00562ccd4e88d092b9b851df50fad20442bfeb24
• https://git.kernel.org/stable/c/3516a4131c4e45d62ee4e42e82c36930e8c1fbbd
• https://git.kernel.org/stable/c/3cde4a8302301679937474a5f7a851394cc1bd11
• https://git.kernel.org/stable/c/79900d978158b2d80eef952fc41b9e4dc58d7b83

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