Out-of-bounds read in Linux kernel - CVE-2026-63807

Vulnerability identifier: #VU138847

CSH Severity: Low

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

CVE-ID: CVE-2026-63807

CWE-ID: CWE-125

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to an out-of-bounds access in the KVM x86 shadow MMU hugepage recovery logic when recovering hugepages for a direct shadow page whose gfn falls outside the target memslot. A local user can create a guest hugepage mapping that extends below the bounds of a memslot to cause a denial of service.

The issue can manifest as a host page fault in kernel mode during hugepage recovery.

Linux kernel
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
openEuler
Ubuntu
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
bpftool
kernel-source
kernel (Red Hat package)
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
kernel - update to 5.10.0-328.0.0.229
python3-perf-debuginfo - update to 5.10.0-328.0.0.229
python3-perf - update to 5.10.0-328.0.0.229
perf-debuginfo - update to 5.10.0-328.0.0.229
perf - update to 5.10.0-328.0.0.229
kernel-tools-devel - update to 5.10.0-328.0.0.229
kernel-tools-debuginfo - update to 5.10.0-328.0.0.229
kernel-tools - update to 5.10.0-328.0.0.229
kernel-headers - update to 5.10.0-328.0.0.229
kernel-devel - update to 5.10.0-328.0.0.229
kernel-debugsource - update to 5.10.0-328.0.0.229
kernel-debuginfo - update to 5.10.0-328.0.0.229
bpftool-debuginfo - update to 5.10.0-328.0.0.229
bpftool - update to 5.10.0-328.0.0.229
kernel-source - update to 5.10.0-328.0.0.229
kernel (Red Hat package) - update to 6.12.0-55.94.1.el10_0
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/18587f9831612e24cd8f24be1ec15478feff7abc
• https://git.kernel.org/stable/c/48b91ed7e22bb82571c34f8b80b6ecdc90a6fab8
• https://git.kernel.org/stable/c/5cab1c989f938f5e1b9a0de66486f1fc2c28479b
• https://git.kernel.org/stable/c/7b52008023b7facf40fba3ebe92449bda8ea53b9
• https://git.kernel.org/stable/c/b2ae3245ea44dccaa9af676b6747476951883318
• https://git.kernel.org/stable/c/c5c29b3c268332afe67d598a034c58344540ed92
• https://git.kernel.org/stable/c/ef057cbf825e03b63f6edf5980f96abf3c53089d

• Out-of-bounds read in Linux kernel KVM x86 shadow MMU hugepage recovery logic
• Red Hat Enterprise Linux 10 update for kernel
• openEuler 22.03 LTS SP4 update for kernel
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-gcp-7.0