Use-after-free in Linux kernel - CVE-2026-64397

Vulnerability identifier: #VU139567

CSH Severity: Medium

CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-64397

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

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

The vulnerability exists due to a use-after-free in smb2_query_dir() and the ksmbd directory enumeration state when handling concurrent QUERY_DIRECTORY requests using the same file handle. A remote user can send concurrent QUERY_DIRECTORY requests on the same file handle to cause a denial of service.

The issue occurs because a pointer to stack-allocated private data is stored in shared readdir state and can be overwritten while an iterate_dir() callback is still using it.

Linux kernel
openEuler
Ubuntu
bpftool
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
kernel
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 5.10.0-327.0.0.228
python3-perf-debuginfo - update to 5.10.0-327.0.0.228
python3-perf - update to 5.10.0-327.0.0.228
perf-debuginfo - update to 5.10.0-327.0.0.228
perf - update to 5.10.0-327.0.0.228
kernel-tools-devel - update to 5.10.0-327.0.0.228
kernel-tools-debuginfo - update to 5.10.0-327.0.0.228
kernel-tools - update to 5.10.0-327.0.0.228
kernel-source - update to 5.10.0-327.0.0.228
kernel-headers - update to 5.10.0-327.0.0.228
kernel-devel - update to 5.10.0-327.0.0.228
kernel-debugsource - update to 5.10.0-327.0.0.228
kernel-debuginfo - update to 5.10.0-327.0.0.228
bpftool-debuginfo - update to 5.10.0-327.0.0.228
kernel - update to 5.10.0-327.0.0.228
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/1426fd79102539bc0ab5c8fced047ad4313b9908
• https://git.kernel.org/stable/c/2a64dbf9c739ddf7a25a066507597bf89f8f73d2
• https://git.kernel.org/stable/c/64dac2d486ec1eb18dc00968b16a230b6b75ec24
• https://git.kernel.org/stable/c/a1d5d31cad593ea5e1b637f2f39c9ef6d09d1199
• https://git.kernel.org/stable/c/be6d26bf27499977c746abc163659915082348d8
• https://git.kernel.org/stable/c/fd22b039a5a05bc1d6818e9dcd1001fb432a829d

• Use-after-free in Linux kernel smb server
• 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