Always-Incorrect Control Flow Implementation in Linux kernel - CVE-2026-31398

Vulnerability identifier: #VU124883

CSH Severity: Low

CVSS v4 BT: 4.3 [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/E:U/U:Clear]

CVE-ID: CVE-2026-31398

CWE-ID: CWE-670

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 incorrect pte restoration in folio_unmap_pte_batch() when restoring page table entries for lazyfree folios during reclaim. A local user can trigger a crafted memory-management sequence to cause a denial of service.

The issue can lead to a kernel BUG and crash when a batch contains a mix of writable and non-writable bits, causing writable mappings to be restored incorrectly and breaking anonymous memory copy-on-write semantics.

Linux kernel
openEuler
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
bpftool
kernel
kernel-extra-modules

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
python3-perf-debuginfo - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
python3-perf - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
perf-debuginfo - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
perf - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools-devel - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools-debuginfo - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-tools - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-source - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-headers - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-devel - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-debugsource - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-debuginfo - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
bpftool-debuginfo - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
bpftool - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel - addressed in versions 6.6.0-145.1.14.152, 6.6.0-145.3.14.145
kernel-extra-modules - update to 6.6.0-145.3.14.145

• https://git.kernel.org/stable/c/29f40594a28114b9a9bc87f6cf7bbee9609628f2
• https://git.kernel.org/stable/c/99888a4f340ca8e839a0524556bd4db76d63f4e0
• https://git.kernel.org/stable/c/a0911ccdba41b0871abbf8412857bafedec3dbe1

• Always-Incorrect Control Flow Implementation in Linux kernel mm
• openEuler 24.03 LTS SP3 update for kernel
• openEuler 24.03 LTS SP1 update for kernel