Integer underflow in Linux kernel - CVE-2026-64009

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Main Vulnerability Database Vulnerabilities #VU138639

Integer underflow in Linux kernel - CVE-2026-64009

Published: July 20, 2026


Vulnerability identifier: #VU138639
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-2026-64009
CWE-ID: CWE-191
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

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

The vulnerability exists due to an integer underflow leading to an out-of-bounds write in the esp component, specifically xfrm_state_mtu(), when processing a UDP datagram through an IPv4 ESP tunnel SA with attacker-controlled parameters. A local user can install a crafted IPv4 ESP tunnel SA and send a UDP datagram through the tunnel to cause a denial of service.

The issue involves a negative length being sign-extended to size_t before being passed to memset() in esp_output_fill_trailer().


Affected software

Linux kernel
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
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
SUSE Linux Enterprise Live Patching
Legacy Module
Public Cloud Module
Basesystem Module
Development Tools Module
SUSE Real Time Module
Ubuntu
kgraft-patch-4_12_14-122_333-default
kernel-livepatch-SLE15-SP7-RT_Update_21-debugsource
kernel-livepatch-6_4_0-150700_7_78-rt
kernel-livepatch-6_4_0-150700_7_78-rt-debuginfo
kernel-livepatch-6_4_0-150700_53_84-default-debuginfo
kernel-livepatch-6_4_0-150700_53_84-default
kernel-livepatch-SLE15-SP7_Update_22-debugsource
ocfs2-kmp-default-debuginfo
kernel-default-devel
gfs2-kmp-default-debuginfo
gfs2-kmp-default
kernel-default-devel-debuginfo
kernel-macros
kernel-source
kernel-devel
kernel-default-man
cluster-md-kmp-default-debuginfo
kernel-default-base
kernel-syms
kernel-default-base-debuginfo
cluster-md-kmp-default
ocfs2-kmp-default
dlm-kmp-default-debuginfo
dlm-kmp-default
kernel-default-debuginfo
kernel-default-kgraft-devel
kernel-default-debugsource
kernel-default-kgraft
kernel-default
kernel-rt
cluster-md-kmp-rt-debuginfo
kernel-devel-rt
kernel-source-rt
ocfs2-kmp-rt-debuginfo
ocfs2-kmp-rt
gfs2-kmp-rt-debuginfo
gfs2-kmp-rt
dlm-kmp-rt-debuginfo
kernel-rt-debugsource
kernel-syms-rt
dlm-kmp-rt
kernel-rt-devel
kernel-rt-devel-debuginfo
cluster-md-kmp-rt
kernel-rt-debuginfo
kernel-64kb-devel-debuginfo
kernel-zfcpdump
kernel-zfcpdump-debugsource
kernel-zfcpdump-debuginfo
kernel-64kb
kernel-64kb-debuginfo
kernel-default-livepatch-devel
kernel-default-extra-debuginfo
kernel-default-extra
kernel-azure-devel-debuginfo
kernel-azure-debuginfo
kernel-azure-devel
kernel-azure-debugsource
kernel-azure
kernel-default-livepatch
kernel-64kb-debugsource
reiserfs-kmp-default-debuginfo
reiserfs-kmp-default
kernel-obs-build-debugsource
kernel-obs-build
kernel-docs
kernel-64kb-devel
linux (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-gcp (Ubuntu package)
linux-gke (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-azure (Ubuntu package)
linux-ibm (Ubuntu package)
linux-aws (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

How to mitigate CVE-2026-64009

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kgraft-patch-4_12_14-122_333-default - update to 1-8.3.3
kernel-livepatch-SLE15-SP7-RT_Update_21-debugsource - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_78-rt - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_78-rt-debuginfo - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_53_84-default-debuginfo - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_84-default - update to 1-150700.15.3.1
kernel-livepatch-SLE15-SP7_Update_22-debugsource - update to 1-150700.15.3.1
ocfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-devel - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
gfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
gfs2-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-devel-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-macros - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-source - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-devel - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-man - update to 4.12.14-122.333.2
cluster-md-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-base - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1.150700.17.47.1
kernel-syms - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-base-debuginfo - update to 4.12.14-122.333.2
cluster-md-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
ocfs2-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
dlm-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
dlm-kmp-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-kgraft-devel - update to 4.12.14-122.333.2
kernel-default-debugsource - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default-kgraft - update to 4.12.14-122.333.2
kernel-default - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-rt - update to 6.4.0-150700.7.78.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
kernel-devel-rt - update to 6.4.0-150700.7.78.1
kernel-source-rt - update to 6.4.0-150700.7.78.1
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.78.1
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
gfs2-kmp-rt - update to 6.4.0-150700.7.78.1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
kernel-rt-debugsource - update to 6.4.0-150700.7.78.1
kernel-syms-rt - update to 6.4.0-150700.7.78.1
dlm-kmp-rt - update to 6.4.0-150700.7.78.1
kernel-rt-devel - update to 6.4.0-150700.7.78.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.78.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.78.1
kernel-rt-debuginfo - update to 6.4.0-150700.7.78.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.84.1
kernel-zfcpdump - update to 6.4.0-150700.53.84.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.84.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.84.1
kernel-64kb - update to 6.4.0-150700.53.84.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.84.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.84.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.84.1
kernel-default-extra - update to 6.4.0-150700.53.84.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.84.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.84.1
kernel-azure-devel - update to 6.4.0-150700.53.84.1
kernel-azure-debugsource - update to 6.4.0-150700.53.84.1
kernel-azure - update to 6.4.0-150700.53.84.1
kernel-default-livepatch - update to 6.4.0-150700.53.84.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.84.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.84.1
reiserfs-kmp-default - update to 6.4.0-150700.53.84.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.84.1
kernel-obs-build - update to 6.4.0-150700.53.84.1
kernel-docs - update to 6.4.0-150700.53.84.1
kernel-64kb-devel - update to 6.4.0-150700.53.84.1
linux (Ubuntu package) - addressed in versions 5.15.0-195.205~20.04.1, 5.15.0-195.205, 5.15.0-198.208~20.04.1, 5.15.0-198.208+fips1, 5.15.0-1080.84, 5.15.0-1100.108, 5.15.0-1109.111, 5.15.0-1109.114, 5.15.0-1111.115~20.04.1, 5.15.0-1111.115, 5.15.0-1112.118~20.04.1, 5.15.0-1112.118, 5.15.0-1113.119, 5.15.0-1114.120, 5.15.0-1116.125~20.04.1, 5.15.0-1117.124~20.04.1, 5.15.0-1117.124, 5.15.0-1117.124+fips1, 5.15.0-1122.131~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1123.132, 5.15.0-1123.132+fips1, 5.15.0.195.160, 5.15.0.195.205~20.04.1, 5.15.0.198.114, 5.15.0.198.171, 5.15.0.198.208~20.04.1, 5.15.0.1080.83~20.04.1, 5.15.0.1100.99, 5.15.0.1109.105, 5.15.0.1109.113, 5.15.0.1111.108, 5.15.0.1111.115~20.04.1, 5.15.0.1112.111, 5.15.0.1112.118~20.04.1, 5.15.0.1113.112, 5.15.0.1114.110, 5.15.0.1116.120, 5.15.0.1117.113, 5.15.0.1117.120, 5.15.0.1117.124~20.04.1, 5.15.0.1122.131~20.04.1, 5.15.0.1123.107, 5.15.0.1123.121, 5.15.0.1123.132~20.04.1
linux-nvidia (Ubuntu package) - addressed in versions 5.15.0-1112.113, 5.15.0.1112.112, 7.0.0-1016.16~24.04.1, 7.0.0-1016.16
linux-oracle-5.15 (Ubuntu package) - addressed in versions 5.15.0-1114.120~20.04.1, 5.15.0.1114.120~20.04.1
linux-gcp-5.15 (Ubuntu package) - addressed in versions 5.15.0-1118.128~20.04.1, 5.15.0.1118.128~20.04.1
linux-gcp (Ubuntu package) - addressed in versions 5.15.0-1118.128, 5.15.0-1118.128+fips1, 5.15.0.1118.107, 5.15.0.1118.115, 6.8.0-1070.78
linux-gke (Ubuntu package) - addressed in versions 6.8.0-146.146.1~22.04.1, 6.8.0-146.146.1, 6.8.0-1051.55, 6.8.0-1063.66, 6.8.0-1064.67~22.04.1, 6.8.0-1064.67, 6.8.0-1064.67.1, 6.8.0-1065.73, 6.8.0-1066.67
linux-nvidia-tegra (Ubuntu package) - update to 6.8.0-1036.39+1
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1068.75~22.04.1, 6.8.0-1068.75, 6.8.0-1069.77+fips1, 6.8.0-1070.78~22.04.1, 6.8.0-1070.78, 7.0.0-1009.9, 7.0.0-1010.10
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

External References

Related Security Bulletins