Out-of-bounds read in Linux kernel - CVE-2026-23455

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Main Vulnerability Database Vulnerabilities #VU124910

Out-of-bounds read in Linux kernel - CVE-2026-23455

Published: April 6, 2026


Vulnerability identifier: #VU124910
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-23455
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to an out-of-bounds read in DecodeQ931() in the nf_conntrack_h323 netfilter component when parsing a crafted Q.931 packet with a zero UserUserIE length field. A remote attacker can send a specially crafted packet to disclose sensitive information.

The issue occurs because a 16-bit length value is decremented by 1 to skip the protocol discriminator byte, and an encoded length of 0 wraps to -1 and is then passed to DecodeH323_UserInformation() as a large value.


Affected software

Linux kernel
Debian Linux
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Workstation Extension 15
Anolis OS
Red Hat CodeReady Linux Builder for ARM 64
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for Real Time
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
SUSE Linux Enterprise Live Patching
Ubuntu
Public Cloud Module
Legacy Module
Development Tools Module
Basesystem Module
SUSE Real Time Module
openEuler
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
kgraft-patch-4_12_14-122_310-default
kernel-livepatch-6_4_0-150700_7_54-rt-debuginfo
kernel-livepatch-SLE15-SP7-RT_Update_15-debugsource
kernel-livepatch-6_4_0-150700_7_54-rt
kernel-livepatch-6_4_0-150700_53_55-default-debuginfo
kernel-livepatch-SLE15-SP7_Update_15-debugsource
kernel-livepatch-6_4_0-150700_53_55-default
kernel (Red Hat package)
kernel-rt (Red Hat package)
linux (Ubuntu package)
linux-aws (Ubuntu package)
kernel-macros
gfs2-kmp-default-debuginfo
kernel-default-man
kernel-devel
kernel-source
kernel-default
kernel-default-debuginfo
kernel-default-base
kernel-default-debugsource
dlm-kmp-default
cluster-md-kmp-default
ocfs2-kmp-default-debuginfo
kernel-default-base-debuginfo
ocfs2-kmp-default
kernel-default-devel
dlm-kmp-default-debuginfo
cluster-md-kmp-default-debuginfo
kernel-syms
gfs2-kmp-default
kernel-default-kgraft
kernel-default-kgraft-devel
kernel-default-devel-debuginfo
linux-azure (Ubuntu package)
linux-aws-hwe (Ubuntu package)
kernel-core
bpftool
kernel
kernel-cross-headers
kernel-debug
kernel-debug-core
kernel-debug-devel
kernel-debug-modules
kernel-debug-modules-extra
kernel-headers
kernel-modules
kernel-modules-extra
kernel-tools
kernel-tools-libs
kernel-tools-libs-devel
perf
python3-perf
kernel-abi-stablelists
kernel-doc
linux-ibm (Ubuntu package)
linux-raspi (Ubuntu package)
linux-kvm (Ubuntu package)
linux-xilinx-zynqmp (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux (Debian package)
dlm-kmp-rt-debuginfo
dlm-kmp-rt
ocfs2-kmp-rt-debuginfo
kernel-rt
kernel-source-rt
kernel-devel-rt
gfs2-kmp-rt-debuginfo
cluster-md-kmp-rt
ocfs2-kmp-rt
kernel-syms-rt
gfs2-kmp-rt
kernel-rt-debugsource
cluster-md-kmp-rt-debuginfo
kernel-rt-debuginfo
kernel-rt-devel-debuginfo
kernel-rt-devel
kernel-obs-build-debugsource
kernel-obs-build
kernel-docs
kernel-zfcpdump-debugsource
kernel-zfcpdump-debuginfo
kernel-zfcpdump
kernel-64kb-debuginfo
kernel-64kb-devel
kernel-64kb-debugsource
kernel-64kb-devel-debuginfo
kernel-64kb
reiserfs-kmp-default-debuginfo
kernel-default-livepatch-devel
kernel-default-livepatch
kernel-default-extra
kernel-default-extra-debuginfo
kernel-azure-devel
kernel-azure-devel-debuginfo
kernel-azure-debuginfo
kernel-azure-debugsource
kernel-azure
reiserfs-kmp-default
python3-perf-debuginfo
perf-debuginfo
kernel-tools-devel
kernel-tools-debuginfo
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel-extra-modules
linux-hwe-6.8 (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-raspi-realtime (Ubuntu package)
linux-hwe-6.17 (Ubuntu package)
linux-azure-fde-6.17 (Ubuntu package)
linux-azure-6.17 (Ubuntu package)
linux-nvidia-6.17 (Ubuntu package)
linux-oem-6.17 (Ubuntu package)

How to mitigate CVE-2026-23455

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kgraft-patch-4_12_14-122_310-default - update to 1-8.3.1
kernel-livepatch-6_4_0-150700_7_54-rt-debuginfo - update to 1-150700.1.3.1
kernel-livepatch-SLE15-SP7-RT_Update_15-debugsource - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_54-rt - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_53_55-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-SLE15-SP7_Update_15-debugsource - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_55-default - update to 1-150700.15.3.1
kernel (Red Hat package) - addressed in versions 3.10.0-1160.154.1.el7, 4.18.0-305.197.1.el8_4, 4.18.0-372.198.1.el8_6, 4.18.0-477.150.1.el8_8, 4.18.0-553.126.1.el8_10, 5.14.0-284.176.1.el9_2
kernel-rt (Red Hat package) - addressed in versions 3.10.0-1160.155.1.rt56.1307.el7, 4.18.0-553.126.1.rt7.467.el8_10, 5.14.0-284.176.1.rt14.461.el9_2
linux (Ubuntu package) - addressed in versions 3.13.0.214.224, 3.13.0-214.265, 4.4.0.283.289, 4.4.0-283.317, 4.4.0.1157.154, 4.4.0-1157.168, 4.4.0.1194.198, 4.4.0-1194.209, 4.15.0.253.237, 4.15.0-253.265, 4.15.0.1149.146, 4.15.0-1149.161, 4.15.0.1156.161, 4.15.0-1156.167, 4.15.0.1176.167, 4.15.0-1176.181, 4.15.0.1187.200~16.04.1, 4.15.0-1187.204, 4.15.0.1204.172, 4.15.0-1204.219, 4.15.0.2095.93, 4.15.0-2095.101, 4.15.0.2112.108, 4.15.0-2112.118, 5.4.0.233.225, 5.4.0-233.253, 5.4.0-233.253~18.04.1, 5.4.0-1065.68, 5.4.0.1079.79, 5.4.0-1079.83, 5.4.0.1120.116, 5.4.0-1120.127, 5.4.0.1135.132, 5.4.0-1135.145, 5.4.0.1159.153, 5.4.0-1159.169+fips1, 5.4.0-1159.169~18.04.1, 5.4.0.1161.108, 5.4.0.1161.159, 5.4.0-1161.172, 5.4.0-1161.172+fips1, 5.4.0-1161.172~18.04.1, 5.4.0.1164.106, 5.4.0.1164.166, 5.4.0-1164.173, 5.4.0-1164.173+fips1, 5.4.0-1164.173~18.04.1, 5.4.0.1166.102, 5.4.0.1166.158, 5.4.0-1166.172, 5.4.0-1166.172+fips1, 5.4.0-1166.172~18.04.1, 5.15.0.183.154, 5.15.0-183.193, 5.15.0-183.193~20.04.1, 5.15.0.185.108, 5.15.0.185.166, 5.15.0-185.195+fips1, 5.15.0-185.195~20.04.1, 5.15.0-1052.52, 5.15.0.1052.54, 5.15.0-1063.63, 5.15.0-1063.63~20.04.1, 5.15.0.1094.93, 5.15.0-1094.102, 5.15.0.1103.99, 5.15.0-1103.105, 5.15.0.1103.107, 5.15.0-1103.108, 5.15.0.1105.102, 5.15.0.1105.109, 5.15.0-1105.109~20.04.1, 5.15.0.1106.105, 5.15.0.1106.106, 5.15.0-1106.107, 5.15.0-1106.112, 5.15.0.1107.106, 5.15.0-1107.113, 5.15.0.1108.104, 5.15.0-1108.114, 5.15.0.1110.114, 5.15.0-1110.119, 5.15.0.1111.101, 5.15.0.1111.107, 5.15.0.1111.108, 5.15.0.1111.114, 5.15.0-1111.118, 5.15.0-1111.118+fips1, 5.15.0-1111.118~20.04.1, 5.15.0-1111.121, 5.15.0-1111.121+fips1, 5.15.0.1116.114, 5.15.0-1116.125, 5.15.0-1116.125~20.04.1, 6.8.0-134.134, 6.8.0-1057.58~22.04.1, 6.8.0-1058.61+fips1, 6.8.0-1058.61~22.04.1, 6.8.0-1060.61, 6.8.0-1060.63+fips1, 6.8.0-1060.63~22.04.1, 6.8.0-1063.69, 6.8.0-1063.69+fips1, 6.8.1-1055.56, 6.8.1-1055.56~22.04.1, 6.17.0-40.40
linux-aws (Ubuntu package) - addressed in versions 4.4.0-283.317~14.04.1, 4.4.0.1126.128, 4.4.0-1126.133, 4.4.0.1156.153, 4.4.0-1156.162, 4.15.0.1194.192, 4.15.0-1194.207, 4.15.0.2132.126, 4.15.0-2132.138
kernel-macros - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
gfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-man - update to 4.12.14-122.310.1
kernel-devel - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-source - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-base - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1.150700.17.33.1
kernel-default-debugsource - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
dlm-kmp-default - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
cluster-md-kmp-default - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
ocfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-base-debuginfo - update to 4.12.14-122.310.1
ocfs2-kmp-default - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-devel - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
dlm-kmp-default-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
cluster-md-kmp-default-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-syms - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
gfs2-kmp-default - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
kernel-default-kgraft - update to 4.12.14-122.310.1
kernel-default-kgraft-devel - update to 4.12.14-122.310.1
kernel-default-devel-debuginfo - addressed in versions 4.12.14-122.310.1, 6.4.0-150700.53.55.1
linux-azure (Ubuntu package) - addressed in versions 4.15.0-253.265~16.04.1, 4.15.0-254.266~16.04.1, 4.15.0-1156.167~16.04.1, 4.15.0-1188.205~16.04.1, 4.15.0-1205.220~14.04.1, 4.15.0-1205.220~16.04.1, 6.8.0-1063.71, 6.8.0-1063.71~22.04.1
linux-aws-hwe (Ubuntu package) - update to 4.15.0-1195.208~16.04.1
kernel-core - update to 4.18.0-553.126.1.0.1
bpftool - update to 4.18.0-553.126.1.0.1
kernel - update to 4.18.0-553.126.1.0.1
kernel-cross-headers - update to 4.18.0-553.126.1.0.1
kernel-debug - update to 4.18.0-553.126.1.0.1
kernel-debug-core - update to 4.18.0-553.126.1.0.1
kernel-debug-devel - update to 4.18.0-553.126.1.0.1
kernel-debug-modules - update to 4.18.0-553.126.1.0.1
kernel-debug-modules-extra - update to 4.18.0-553.126.1.0.1
kernel-devel - update to 4.18.0-553.126.1.0.1
kernel-headers - update to 4.18.0-553.126.1.0.1
kernel-modules - update to 4.18.0-553.126.1.0.1
kernel-modules-extra - update to 4.18.0-553.126.1.0.1
kernel-tools - update to 4.18.0-553.126.1.0.1
kernel-tools-libs - update to 4.18.0-553.126.1.0.1
kernel-tools-libs-devel - update to 4.18.0-553.126.1.0.1
perf - update to 4.18.0-553.126.1.0.1
python3-perf - update to 4.18.0-553.126.1.0.1
kernel-abi-stablelists - update to 4.18.0-553.126.1.0.1
kernel-doc - update to 4.18.0-553.126.1.0.1
linux-ibm (Ubuntu package) - addressed in versions 5.4.0-1107.112, 5.4.0-1107.112~18.04.1, 5.4.0.1107.136
linux-raspi (Ubuntu package) - addressed in versions 5.4.0-1144.157, 5.4.0-1144.157~18.04.1, 5.4.0.1144.175, 5.15.0.1105.103, 5.15.0-1105.108, 6.8.0-1060.64, 6.17.0-1021.21
linux-kvm (Ubuntu package) - addressed in versions 5.4.0.1148.144, 5.4.0-1148.157
linux-xilinx-zynqmp (Ubuntu package) - addressed in versions 5.15.0.1074.77, 5.15.0-1074.78
linux-gcp-5.15 (Ubuntu package) - addressed in versions 5.15.0-1106.112~20.04.1, 5.15.0-1111.121~20.04.1
linux-oracle-5.15 (Ubuntu package) - update to 5.15.0-1108.114~20.04.1
linux-azure-fips (Ubuntu package) - addressed in versions 5.15.0.1116.101, 5.15.0-1116.125+fips1, 6.8.0-134.134+fips1, 6.8.0-1062.69+fips1
linux (Debian package) - addressed in versions 6.1.170-1, 6.12.85-1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
dlm-kmp-rt - update to 6.4.0-150700.7.54.1
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt - update to 6.4.0-150700.7.54.1
kernel-source-rt - update to 6.4.0-150700.7.54.1
kernel-devel-rt - update to 6.4.0-150700.7.54.1
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.54.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-syms-rt - update to 6.4.0-150700.7.54.1
gfs2-kmp-rt - update to 6.4.0-150700.7.54.1
kernel-rt-debugsource - update to 6.4.0-150700.7.54.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.54.1
kernel-rt-devel - update to 6.4.0-150700.7.54.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.55.1
kernel-obs-build - update to 6.4.0-150700.53.55.1
kernel-docs - update to 6.4.0-150700.53.55.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.55.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.55.1
kernel-zfcpdump - update to 6.4.0-150700.53.55.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb-devel - update to 6.4.0-150700.53.55.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.55.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-64kb - update to 6.4.0-150700.53.55.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.55.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.55.1
kernel-default-livepatch - update to 6.4.0-150700.53.55.1
kernel-default-extra - update to 6.4.0-150700.53.55.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.55.1
kernel-azure-devel - update to 6.4.0-150700.53.55.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.55.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.55.1
kernel-azure-debugsource - update to 6.4.0-150700.53.55.1
kernel-azure - update to 6.4.0-150700.53.55.1
reiserfs-kmp-default - update to 6.4.0-150700.53.55.1
bpftool - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
python3-perf-debuginfo - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
python3-perf - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
perf-debuginfo - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
perf - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-tools-devel - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-tools-debuginfo - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-tools - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-source - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-headers - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-devel - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-debugsource - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-debuginfo - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
bpftool-debuginfo - addressed in versions 6.6.0-145.0.7.134, 6.6.0-145.0.7.138, 6.6.0-145.0.7.146
kernel-extra-modules - update to 6.6.0-145.0.7.138
linux-hwe-6.8 (Ubuntu package) - update to 6.8.0-136.136~22.04.1
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1029.30
linux-aws-6.8 (Ubuntu package) - addressed in versions 6.8.0-1045.48, 6.8.0-1057.58~22.04.1, 6.8.0-1058.61.1, 6.8.0-1058.64, 6.8.0-1060.61~22.04.1, 6.8.0-1060.63~22.04.1, 6.8.0-1063.69~22.04.1
linux-azure-fde (Ubuntu package) - update to 6.8.0-1062.69
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1062.69~22.04.1
linux-raspi-realtime (Ubuntu package) - update to 6.8.0-2049.50
linux-hwe-6.17 (Ubuntu package) - update to 6.17.0-40.40~24.04.1
linux-azure-fde-6.17 (Ubuntu package) - update to 6.17.0-1018.18~24.04.1
linux-azure-6.17 (Ubuntu package) - update to 6.17.0-1021.21~24.04.1
linux-nvidia-6.17 (Ubuntu package) - update to 6.17.0-1026.26
linux-oem-6.17 (Ubuntu package) - update to 6.17.0-1028.28

External References

Related Security Bulletins