Use-after-free in Linux kernel - CVE-2026-63993

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Main Vulnerability Database Vulnerabilities #VU138657

Use-after-free in Linux kernel - CVE-2026-63993

Published: July 20, 2026


Vulnerability identifier: #VU138657
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63993
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to execute arbitrary code.

The vulnerability exists due to a use-after-free in the vxlan_xmit_one function in drivers/net/vxlan/vxlan_core.c when processing packets after skb_tunnel_check_pmtu() updates the skb head. A local user can trigger the vulnerable code path to execute arbitrary code.


Affected software

Linux kernel
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Workstation Extension 15
SUSE Linux Enterprise High Availability Extension 15
SUSE Linux Enterprise Desktop 15
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Legacy Module
Development Tools Module
Basesystem Module
Public Cloud Module
SUSE Linux Enterprise Live Patching
SUSE Real Time Module
Ubuntu
openEuler
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-SLE15-SP7_Update_22-debugsource
kernel-livepatch-6_4_0-150700_53_84-default
kernel (Red Hat package)
kernel-rt
kernel-rt-devel-debuginfo
kernel-rt-devel
dlm-kmp-rt
kernel-syms-rt
kernel-rt-debuginfo
cluster-md-kmp-rt-debuginfo
ocfs2-kmp-rt-debuginfo
kernel-rt-debugsource
kernel-devel-rt
kernel-source-rt
ocfs2-kmp-rt
gfs2-kmp-rt-debuginfo
gfs2-kmp-rt
dlm-kmp-rt-debuginfo
cluster-md-kmp-rt
reiserfs-kmp-default-debuginfo
kernel-obs-build
kernel-64kb-devel-debuginfo
dlm-kmp-default-debuginfo
reiserfs-kmp-default
kernel-source
kernel-64kb-debugsource
kernel-64kb-devel
kernel-docs
kernel-obs-build-debugsource
kernel-syms
kernel-default
kernel-default-debugsource
cluster-md-kmp-default
gfs2-kmp-default-debuginfo
dlm-kmp-default
gfs2-kmp-default
ocfs2-kmp-default
cluster-md-kmp-default-debuginfo
kernel-default-debuginfo
ocfs2-kmp-default-debuginfo
kernel-64kb-debuginfo
kernel-default-devel
kernel-default-devel-debuginfo
kernel-devel
kernel-macros
kernel-zfcpdump
kernel-zfcpdump-debugsource
kernel-zfcpdump-debuginfo
kernel-64kb
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-default-livepatch-devel
kernel-default-base
python3-perf
python3-perf-debuginfo
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel
kernel-tools
kernel-headers
kernel-extra-modules
kernel-debugsource
kernel-debuginfo
bpftool
bpftool-debuginfo
linux-aws (Ubuntu package)
linux (Ubuntu package)
linux-fips (Ubuntu package)
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux-ibm-5.15 (Ubuntu package)
linux-aws-5.15 (Ubuntu package)
linux-oracle-5.15 (Ubuntu package)
linux-gcp-5.15 (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure (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-2026-63993

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
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-SLE15-SP7_Update_22-debugsource - update to 1-150700.15.3.1
kernel-livepatch-6_4_0-150700_53_84-default - update to 1-150700.15.3.1
kernel (Red Hat package) - addressed in versions 5.14.0-687.55.1.el9_8, 6.12.0-55.111.1.el10_0
kernel-rt - update to 6.4.0-150700.7.78.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.78.1
kernel-rt-devel - update to 6.4.0-150700.7.78.1
dlm-kmp-rt - update to 6.4.0-150700.7.78.1
kernel-syms-rt - update to 6.4.0-150700.7.78.1
kernel-rt-debuginfo - update to 6.4.0-150700.7.78.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
ocfs2-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-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 - 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
cluster-md-kmp-rt - update to 6.4.0-150700.7.78.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.84.1
kernel-obs-build - update to 6.4.0-150700.53.84.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.84.1
dlm-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-source - update to 6.4.0-150700.53.84.1
kernel-64kb-debugsource - update to 6.4.0-150700.53.84.1
kernel-64kb-devel - update to 6.4.0-150700.53.84.1
kernel-docs - update to 6.4.0-150700.53.84.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.84.1
kernel-syms - update to 6.4.0-150700.53.84.1
kernel-default - update to 6.4.0-150700.53.84.1
kernel-default-debugsource - update to 6.4.0-150700.53.84.1
cluster-md-kmp-default - update to 6.4.0-150700.53.84.1
gfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.84.1
dlm-kmp-default - update to 6.4.0-150700.53.84.1
gfs2-kmp-default - update to 6.4.0-150700.53.84.1
ocfs2-kmp-default - update to 6.4.0-150700.53.84.1
cluster-md-kmp-default-debuginfo - update to 6.4.0-150700.53.84.1
kernel-default-debuginfo - update to 6.4.0-150700.53.84.1
ocfs2-kmp-default-debuginfo - update to 6.4.0-150700.53.84.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.84.1
kernel-default-devel - update to 6.4.0-150700.53.84.1
kernel-default-devel-debuginfo - update to 6.4.0-150700.53.84.1
kernel-devel - update to 6.4.0-150700.53.84.1
kernel-macros - 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-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-default-livepatch-devel - update to 6.4.0-150700.53.84.1
kernel-default-base - update to 6.4.0-150700.53.84.1.150700.17.47.1
python3-perf - update to 6.6.0-145.3.29.160
python3-perf-debuginfo - update to 6.6.0-145.3.29.160
perf-debuginfo - update to 6.6.0-145.3.29.160
perf - update to 6.6.0-145.3.29.160
kernel-tools-devel - update to 6.6.0-145.3.29.160
kernel-tools-debuginfo - update to 6.6.0-145.3.29.160
kernel - update to 6.6.0-145.3.29.160
kernel-tools - update to 6.6.0-145.3.29.160
kernel-source - update to 6.6.0-145.3.29.160
kernel-headers - update to 6.6.0-145.3.29.160
kernel-extra-modules - update to 6.6.0-145.3.29.160
kernel-devel - update to 6.6.0-145.3.29.160
kernel-debugsource - update to 6.6.0-145.3.29.160
kernel-debuginfo - update to 6.6.0-145.3.29.160
bpftool - update to 6.6.0-145.3.29.160
bpftool-debuginfo - update to 6.6.0-145.3.29.160
linux-aws (Ubuntu package) - addressed in versions 5.15.0-194.204~20.04.1, 5.15.0-194.204, 5.15.0-1079.83, 5.15.0-1099.107, 5.15.0-1108.110, 5.15.0-1108.113, 5.15.0-1110.114, 5.15.0-1111.117, 5.15.0-1112.118, 5.15.0-1113.119, 5.15.0-1115.124, 5.15.0-1116.123, 5.15.0-1116.123+fips1, 5.15.0-1116.126+fips1, 5.15.0-1117.127, 5.15.0-1121.130, 5.15.0-1122.131, 5.15.0-1122.131+fips1, 5.15.0.194.159, 5.15.0.1079.82, 5.15.0.1099.98, 5.15.0.1108.104, 5.15.0.1108.112, 5.15.0.1110.107, 5.15.0.1111.110, 5.15.0.1112.111, 5.15.0.1113.109, 5.15.0.1115.119, 5.15.0.1116.106, 5.15.0.1116.112, 5.15.0.1116.119, 5.15.0.1117.114, 5.15.0.1122.106, 5.15.0.1122.120, 6.8.0-1065.68~22.04.1, 6.8.0-1065.68, 7.0.0-1009.9, 7.0.0-1015.15
linux (Ubuntu package) - addressed in versions 5.15.0-194.204, 5.15.0-1111.112, 5.15.0.194.171, 5.15.0.1111.111, 6.8.0-142.142+fips1, 6.8.0-142.142.1~22.04.1, 6.8.0-142.142.1, 6.8.0-1050.54, 6.8.0-1062.65~22.04.1, 6.8.0-1064.72+fips1, 6.8.0-1065.66, 6.8.0-1065.69, 6.8.0-1066.73~22.04.1, 6.8.0-1066.73, 6.8.0-1068.76~22.04.1, 6.8.0-1068.76, 6.8.0-1068.76+fips1, 6.8.0-1069.77~22.04.1, 6.8.0-1069.77, 6.8.0-2054.56, 6.8.1-1060.61~22.04.1, 6.8.1-1060.61
linux-fips (Ubuntu package) - addressed in versions 5.15.0-194.204+fips1, 5.15.0.194.113
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1057.57, 5.15.0-1068.70, 5.15.0.1057.59, 5.15.0.1068.68, 6.8.0-1035.38
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1068.70~20.04.1
linux-ibm-5.15 (Ubuntu package) - update to 5.15.0-1110.114~20.04.1
linux-aws-5.15 (Ubuntu package) - addressed in versions 5.15.0-1111.117~20.04.1, 5.15.0-1116.123~20.04.1, 5.15.0-1121.130~20.04.1, 5.15.0-1122.131~20.04.1
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-nvidia (Ubuntu package) - addressed in versions 6.8.0-1063.66~22.04.1, 6.8.0-1063.66, 6.8.0-1063.66.1, 7.0.0-1016.16~24.04.1, 7.0.0-1016.16
linux-aws-fips (Ubuntu package) - update to 6.8.0-1065.68+fips1
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
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