Improper input validation in Linux kernel - CVE-2026-63956

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Main Vulnerability Database Vulnerabilities #VU138693

Improper input validation in Linux kernel - CVE-2026-63956

Published: July 20, 2026


Vulnerability identifier: #VU138693
CSH Severity: Medium
CVSS v4: 5.2 [CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63956
CWE-ID: CWE-20
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows an attacker with physical access to cause a denial of service or corrupt memory.

The vulnerability exists due to improper input validation in the cypress_m8 USB serial driver when processing a malicious USB device with a too-small interrupt-out endpoint max packet size. An attacker with physical access can connect a specially crafted USB device to cause a denial of service or corrupt memory.

The issue can be triggered if a device reports an interrupt-out endpoint max packet size smaller than eight bytes.


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
openEuler
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-SLE15-SP7_Update_22-debugsource
kernel-livepatch-6_4_0-150700_53_84-default
dlm-kmp-default
kernel-default-kgraft-devel
dlm-kmp-default-debuginfo
ocfs2-kmp-default
cluster-md-kmp-default
kernel-default-base-debuginfo
kernel-syms
kernel-default-base
cluster-md-kmp-default-debuginfo
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
kernel-default-debuginfo
kernel-default
kernel-default-kgraft
kernel-default-debugsource
python3-perf-debuginfo
kernel
bpftool
bpftool-debuginfo
kernel-debuginfo
kernel-debugsource
kernel-headers
kernel-tools
kernel-tools-debuginfo
kernel-tools-devel
perf
perf-debuginfo
python3-perf
ocfs2-kmp-rt-debuginfo
kernel-rt
kernel-rt-debuginfo
ocfs2-kmp-rt
gfs2-kmp-rt-debuginfo
gfs2-kmp-rt
cluster-md-kmp-rt-debuginfo
dlm-kmp-rt-debuginfo
kernel-source-rt
kernel-devel-rt
cluster-md-kmp-rt
kernel-rt-debugsource
kernel-syms-rt
dlm-kmp-rt
kernel-rt-devel
kernel-rt-devel-debuginfo
reiserfs-kmp-default-debuginfo
kernel-64kb-debuginfo
kernel-64kb-devel-debuginfo
kernel-64kb-debugsource
kernel-64kb-devel
kernel-docs
kernel-obs-build
kernel-obs-build-debugsource
reiserfs-kmp-default
kernel-azure-debugsource
kernel-64kb
kernel-zfcpdump
kernel-zfcpdump-debugsource
kernel-zfcpdump-debuginfo
kernel-default-livepatch
kernel-default-livepatch-devel
kernel-azure
kernel-azure-devel
kernel-azure-debuginfo
kernel-default-extra-debuginfo
kernel-default-extra
kernel-azure-devel-debuginfo
kernel-extra-modules
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-2026-63956

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-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
dlm-kmp-default - 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
dlm-kmp-default-debuginfo - 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
cluster-md-kmp-default - 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
kernel-syms - 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
cluster-md-kmp-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
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
kernel-default-debuginfo - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
kernel-default - 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-debugsource - addressed in versions 4.12.14-122.333.2, 6.4.0-150700.53.84.1
python3-perf-debuginfo - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool-debuginfo - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-debuginfo - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-debugsource - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-devel - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-headers - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-source - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-debuginfo - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-devel - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
perf - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
perf-debuginfo - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python3-perf - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
ocfs2-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
kernel-rt - update to 6.4.0-150700.7.78.1
kernel-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
cluster-md-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
dlm-kmp-rt-debuginfo - update to 6.4.0-150700.7.78.1
kernel-source-rt - update to 6.4.0-150700.7.78.1
kernel-devel-rt - update to 6.4.0-150700.7.78.1
cluster-md-kmp-rt - 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
reiserfs-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-64kb-devel-debuginfo - 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 - update to 6.4.0-150700.53.84.1
kernel-obs-build-debugsource - update to 6.4.0-150700.53.84.1
reiserfs-kmp-default - update to 6.4.0-150700.53.84.1
kernel-azure-debugsource - update to 6.4.0-150700.53.84.1
kernel-64kb - 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-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-azure - update to 6.4.0-150700.53.84.1
kernel-azure-devel - update to 6.4.0-150700.53.84.1
kernel-azure-debuginfo - 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-extra-modules - 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