Improper access control in Linux kernel - CVE-2026-63830

Vulnerability identifier: #VU138821

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63830

CWE-ID: CWE-284

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to modify the page cache contents.

The vulnerability exists due to improper access control in the sk_msg scatter-gather handling logic when processing SK_MSG transformations and BPF message helpers. A local user can trigger scatterlist entry transfers, shifts, splits, or copies that desynchronize sg.copy state to modify the page cache contents.

Exploitation requires the ability to reach a later SK_MSG verdict that exposes sg_virt(sge) as writable BPF ctx->data.

Linux kernel
openEuler
Ubuntu
bpftool
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-headers
kernel-extra-modules
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel
kernel-source
linux (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
bpftool - update to 6.6.0-145.3.29.160
python3-perf-debuginfo - update to 6.6.0-145.3.29.160
python3-perf - update to 6.6.0-145.3.29.160
perf-debuginfo - update to 6.6.0-145.3.29.160
perf - update to 6.6.0-145.3.29.160
kernel-tools-devel - update to 6.6.0-145.3.29.160
kernel-tools-debuginfo - update to 6.6.0-145.3.29.160
kernel-tools - update to 6.6.0-145.3.29.160
kernel-headers - update to 6.6.0-145.3.29.160
kernel-extra-modules - update to 6.6.0-145.3.29.160
kernel-devel - update to 6.6.0-145.3.29.160
kernel-debugsource - update to 6.6.0-145.3.29.160
kernel-debuginfo - update to 6.6.0-145.3.29.160
bpftool-debuginfo - update to 6.6.0-145.3.29.160
kernel - update to 6.6.0-145.3.29.160
kernel-source - update to 6.6.0-145.3.29.160
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13

• https://git.kernel.org/stable/c/0eb4c16c4adb262763bda870a8ed38a1a9dec7ec
• https://git.kernel.org/stable/c/1acdd14c0990dd1cd4b6534f00366d2e6dfce05f
• https://git.kernel.org/stable/c/21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d
• https://git.kernel.org/stable/c/406e8a651a7b854c41fecd5117bb282b3a6c2c6b
• https://git.kernel.org/stable/c/9bb86d8184b37503816150c4a6ad3c17dfdbe827
• https://git.kernel.org/stable/c/d22cc92bc41290e5783a72375e0843d9435f6001

• Improper access control in Linux kernel tls
• openEuler 24.03 LTS SP3 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-gcp-7.0