Uncontrolled Recursion in Linux kernel - CVE-2026-63891

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Main Vulnerability Database Vulnerabilities #VU138758

Uncontrolled Recursion in Linux kernel - CVE-2026-63891

Published: July 20, 2026


Vulnerability identifier: #VU138758
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63891
CWE-ID: CWE-674
Exploitation vector: Adjecent network
Exploit availability: No public exploit available

Vulnerability details

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

The vulnerability exists due to uncontrolled recursion in __tb_property_parse_dir() in the thunderbolt property parser when processing a crafted PROPERTIES_REQUEST control-plane exchange containing chained DIRECTORY entries with a back-reference loop. A remote attacker can send crafted XDomain property data to cause a denial of service.

The issue can be triggered by an untrusted XDomain peer such as a cable, dock, in-line inspector, or adjacent host.


Affected software

Linux kernel
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
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
SUSE Linux Micro
SUSE Linux Micro Extras
SUSE Linux Enterprise Live Patching
Public Cloud Module
Legacy Module
Development Tools Module
Basesystem Module
SUSE Real Time Module
Ubuntu
openEuler
kgraft-patch-4_12_14-122_328-default
kernel-livepatch-6_4_0-150700_7_75-rt-debuginfo
kernel-livepatch-6_4_0-150700_7_75-rt
kernel-livepatch-SLE15-SP7-RT_Update_20-debugsource
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
kernel-macros
dlm-kmp-default-debuginfo
kernel-default-base-debuginfo
ocfs2-kmp-default
dlm-kmp-default
gfs2-kmp-default-debuginfo
ocfs2-kmp-default-debuginfo
gfs2-kmp-default
cluster-md-kmp-default
kernel-default-devel
kernel-default-base
kernel-default-devel-debuginfo
kernel-source
kernel-devel
kernel-default-man
cluster-md-kmp-default-debuginfo
kernel-syms
kernel-default-kgraft
kernel-default-debuginfo
kernel-default-kgraft-devel
kernel-default-debugsource
kernel-default
kernel-rt-livepatch
kernel-64kb-debugsource
kernel-64kb
kernel-64kb-devel
kernel-default-livepatch
kernel-kvmsmall-debugsource
kernel-kvmsmall-debuginfo
kernel-obs-build-debugsource
kernel-obs-build
kernel-rt-debugsource
kernel-rt-debuginfo
kernel-kvmsmall
kernel-source-rt
kernel-devel-rt
kernel-rt
dlm-kmp-rt-debuginfo
cluster-md-kmp-rt-debuginfo
gfs2-kmp-rt-debuginfo
gfs2-kmp-rt
ocfs2-kmp-rt-debuginfo
kernel-syms-rt
kernel-rt-devel-debuginfo
cluster-md-kmp-rt
kernel-rt-devel
dlm-kmp-rt
ocfs2-kmp-rt
kernel-zfcpdump
kernel-zfcpdump-debugsource
kernel-default-extra
kernel-default-extra-debuginfo
kernel-azure-devel-debuginfo
kernel-azure-debuginfo
kernel-azure-debugsource
kernel-azure-devel
kernel-azure
kernel-default-livepatch-devel
kernel-zfcpdump-debuginfo
kernel-64kb-debuginfo
reiserfs-kmp-default-debuginfo
reiserfs-kmp-default
kernel-docs
kernel-64kb-devel-debuginfo
kernel-extra-modules
python3-perf-debuginfo
python3-perf
bpftool
kernel-tools
kernel-tools-debuginfo
kernel-headers
kernel-tools-devel
perf
kernel
bpftool-debuginfo
kernel-debuginfo
perf-debuginfo
kernel-debugsource
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-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-2026-63891

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kgraft-patch-4_12_14-122_328-default - update to 1-8.5.1
kernel-livepatch-6_4_0-150700_7_75-rt-debuginfo - update to 1-150700.1.3.1
kernel-livepatch-6_4_0-150700_7_75-rt - update to 1-150700.1.3.1
kernel-livepatch-SLE15-SP7-RT_Update_20-debugsource - update to 1-150700.1.3.1
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
kernel-macros - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
dlm-kmp-default-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
kernel-default-base-debuginfo - update to 4.12.14-122.328.1
ocfs2-kmp-default - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
dlm-kmp-default - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
gfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
ocfs2-kmp-default-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
gfs2-kmp-default - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
cluster-md-kmp-default - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
kernel-default-devel - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-base - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1.21.35, 6.4.0-52.1.21.36, 6.4.0-150700.53.81.1.150700.17.45.1
kernel-default-devel-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-source - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-devel - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-man - update to 4.12.14-122.328.1
cluster-md-kmp-default-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-150700.53.81.1
kernel-syms - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-kgraft - update to 4.12.14-122.328.1
kernel-default-debuginfo - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-kgraft-devel - update to 4.12.14-122.328.1
kernel-default-debugsource - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default - addressed in versions 4.12.14-122.328.1, 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-rt-livepatch - update to 6.4.0-52.1
kernel-64kb-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-64kb - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-64kb-devel - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-default-livepatch - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-kvmsmall-debugsource - update to 6.4.0-52.1
kernel-kvmsmall-debuginfo - update to 6.4.0-52.1
kernel-obs-build-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-obs-build - addressed in versions 6.4.0-52.1, 6.4.0-150700.53.81.1
kernel-rt-debugsource - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-rt-debuginfo - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-kvmsmall - update to 6.4.0-52.1
kernel-source-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-devel-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
kernel-rt - addressed in versions 6.4.0-52.1, 6.4.0-150700.7.75.1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
gfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
gfs2-kmp-rt - update to 6.4.0-150700.7.75.1
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.75.1
kernel-syms-rt - update to 6.4.0-150700.7.75.1
kernel-rt-devel-debuginfo - update to 6.4.0-150700.7.75.1
cluster-md-kmp-rt - update to 6.4.0-150700.7.75.1
kernel-rt-devel - update to 6.4.0-150700.7.75.1
dlm-kmp-rt - update to 6.4.0-150700.7.75.1
ocfs2-kmp-rt - update to 6.4.0-150700.7.75.1
kernel-zfcpdump - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debugsource - update to 6.4.0-150700.53.81.1
kernel-default-extra - update to 6.4.0-150700.53.81.1
kernel-default-extra-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-debuginfo - update to 6.4.0-150700.53.81.1
kernel-azure-debugsource - update to 6.4.0-150700.53.81.1
kernel-azure-devel - update to 6.4.0-150700.53.81.1
kernel-azure - update to 6.4.0-150700.53.81.1
kernel-default-livepatch-devel - update to 6.4.0-150700.53.81.1
kernel-zfcpdump-debuginfo - update to 6.4.0-150700.53.81.1
kernel-64kb-debuginfo - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default-debuginfo - update to 6.4.0-150700.53.81.1
reiserfs-kmp-default - update to 6.4.0-150700.53.81.1
kernel-docs - update to 6.4.0-150700.53.81.1
kernel-64kb-devel-debuginfo - update to 6.4.0-150700.53.81.1
kernel-extra-modules - update to 6.6.0-145.3.29.160
python3-perf-debuginfo - update to 6.6.0-145.3.29.160
python3-perf - update to 6.6.0-145.3.29.160
bpftool - 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-tools-debuginfo - update to 6.6.0-145.3.29.160
kernel-headers - update to 6.6.0-145.3.29.160
kernel-tools-devel - update to 6.6.0-145.3.29.160
perf - update to 6.6.0-145.3.29.160
kernel - update to 6.6.0-145.3.29.160
bpftool-debuginfo - update to 6.6.0-145.3.29.160
kernel-debuginfo - update to 6.6.0-145.3.29.160
perf-debuginfo - 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
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-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