Use-after-free in Linux kernel - CVE-2026-63823

Vulnerability identifier: #VU138830

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-2026-63823

CWE-ID: CWE-416

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 use-after-free in request_key_auth handling in the Linux kernel key management subsystem when processing KEYCTL_INSTANTIATE_IOV or related key instantiation and rejection paths concurrently with request_key() completion. A local user can trigger concurrent key operations to cause a denial of service.

The issue occurs because the request_key_auth payload can be freed after helper completion while another path later resumes and accesses rka->target_key.

Linux kernel
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Workstation Extension 15
Basesystem Module
Development Tools Module
Legacy Module
Public Cloud Module
SUSE Linux Enterprise Live Patching
openEuler
Ubuntu
kernel-livepatch-6_4_0-150700_53_81-default
kernel-livepatch-6_4_0-150700_53_81-default-debuginfo
kernel-livepatch-SLE15-SP7_Update_21-debugsource
bpftool
kernel
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-tools-debuginfo
bpftool-debuginfo
kernel-debuginfo
kernel-obs-build-debugsource
kernel-obs-build
kernel-syms
kernel-zfcpdump-debugsource
kernel-docs
kernel-64kb-debugsource
kernel-64kb-devel-debuginfo
kernel-64kb-devel
kernel-64kb-debuginfo
kernel-64kb
kernel-zfcpdump-debuginfo
kernel-default-extra
reiserfs-kmp-default
reiserfs-kmp-default-debuginfo
kernel-default-livepatch
kernel-default-livepatch-devel
kernel-azure
kernel-azure-devel
kernel-azure-debugsource
kernel-azure-debuginfo
kernel-azure-devel-debuginfo
kernel-default-extra-debuginfo
gfs2-kmp-default
cluster-md-kmp-default
kernel-default-debuginfo
ocfs2-kmp-default-debuginfo
dlm-kmp-default-debuginfo
ocfs2-kmp-default
gfs2-kmp-default-debuginfo
dlm-kmp-default
kernel-default-debugsource
kernel-default
kernel-default-devel-debuginfo
kernel-default-devel
kernel-macros
kernel-zfcpdump
cluster-md-kmp-default-debuginfo
kernel-default-base
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-livepatch-6_4_0-150700_53_81-default - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_81-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-SLE15-SP7_Update_21-debugsource - update to 1-150700.15.3.1
bpftool - update to 5.10.0-328.0.0.229
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 - update to 5.10.0-328.0.0.229
kernel-source - 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-tools-debuginfo - update to 5.10.0-328.0.0.229
bpftool-debuginfo - update to 5.10.0-328.0.0.229
kernel-debuginfo - update to 5.10.0-328.0.0.229
kernel-obs-build-debugsource - update to 6.4.0-150700.53.81.1
kernel-obs-build - update to 6.4.0-150700.53.81.1
kernel-syms - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.81.1
kernel-docs - update to 6.4.0-150700.53.81.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.81.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb-devel - update to 6.4.0-150700.53.81.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-extra - update to 6.4.0-150700.53.81.1
kernel-source - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-livepatch - update to 6.4.0-150700.53.81.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.81.1
kernel-azure - update to 6.4.0-150700.53.81.1
kernel-azure-devel - update to 6.4.0-150700.53.81.1
kernel-azure-debugsource - update to 6.4.0-150700.53.81.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.81.1
kernel-devel - update to 6.4.0-150700.53.81.1
gfs2-kmp-default - update to 6.4.0-150700.53.81.1
cluster-md-kmp-default - update to 6.4.0-150700.53.81.1
kernel-default-debuginfo - update to 6.4.0-150700.53.81.1
ocfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
dlm-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
ocfs2-kmp-default - update to 6.4.0-150700.53.81.1
gfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
dlm-kmp-default - update to 6.4.0-150700.53.81.1
kernel-default-debugsource - update to 6.4.0-150700.53.81.1
kernel-default - update to 6.4.0-150700.53.81.1
kernel-default-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-devel - update to 6.4.0-150700.53.81.1
kernel-macros - update to 6.4.0-150700.53.81.1
kernel-zfcpdump - update to 6.4.0-150700.53.81.1
cluster-md-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
kernel-default-base - update to 6.4.0-150700.53.81.1.150700.17.45.1
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/35ab4db86774d82389e4b9559e26ab7f68d8e395
• https://git.kernel.org/stable/c/4982bfabce6b33b3c9eddb4fb900fe5568b7cf91
• https://git.kernel.org/stable/c/708709c65a1832a99b0eef8ae46e343ddaca3d06
• https://git.kernel.org/stable/c/7216ce8cb12fee44e309503955bb83806b106129
• https://git.kernel.org/stable/c/83c0a1cb296d955d5f4d1f0bd8a769ba8ed8c29f
• https://git.kernel.org/stable/c/d8274181b0f28d450b42489723a5ba81042158d7
• https://git.kernel.org/stable/c/f9b68632ac93cc742f2e411021c4dbfe452ea0c2
• https://git.kernel.org/stable/c/fd15b457a86939c38aa12116adabd8ff686c5e51

• Use-after-free in Linux kernel keys
• 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
• SUSE update for the Linux Kernel