Improper input validation in Linux kernel - CVE-2026-53221

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Main Vulnerability Database Vulnerabilities #VU135570

Improper input validation in Linux kernel - CVE-2026-53221

Published: June 26, 2026


Vulnerability identifier: #VU135570
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53221
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause traffic to be associated with the wrong tunnel.

The vulnerability exists due to improper input validation in vti6_tnl_lookup() when matching IPv6 VTI tunnels during fallback wildcard tunnel searches. A remote attacker can send network traffic that triggers a hash collision and incorrect tunnel selection to cause traffic to be associated with the wrong tunnel.

The issue occurs because candidate tunnels in the fallback search were not verified to actually use wildcard local or remote addresses.


Affected software

Linux kernel
Ubuntu
openEuler
linux (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-aws (Ubuntu package)
linux-aws-hwe (Ubuntu package)
perf-debuginfo
python3-perf-debuginfo
python3-perf
python2-perf-debuginfo
python2-perf
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
bpftool
kernel
linux-bluefield (Ubuntu package)
linux-raspi-5.4 (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)
kernel-headers
linux-nvidia (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-aws-7.0 (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-2026-53221

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 4.4.0.288.294, 4.4.0-288.322, 4.4.0-288.322~14.04.1, 4.4.0.1129.131, 4.4.0-1129.136, 4.4.0.1159.156, 4.4.0-1159.165, 4.4.0.1160.157, 4.4.0-1160.171, 4.4.0.1197.201, 4.4.0-1197.212, 4.15.0.260.244, 4.15.0-260.272, 4.15.0-260.272~16.04.2, 4.15.0.1179.170, 4.15.0-1179.184, 5.4.0.241.233, 5.4.0-241.261, 5.4.0-241.261~18.04.1, 5.4.0-1068.71, 5.4.0.1082.82, 5.4.0-1082.86, 5.4.0.1138.135, 5.4.0-1138.148, 5.4.0-1147.160, 5.4.0.1147.178, 5.4.0.1151.147, 5.4.0-1151.160~18.04.1, 5.4.0.1162.156, 5.4.0-1162.172, 5.4.0-1162.172~18.04.1, 5.4.0.1164.162, 5.4.0-1164.175, 5.4.0.1167.109, 5.4.0.1167.170, 5.4.0-1167.176+fips1, 5.4.0-1167.176~18.04.1, 5.4.0-1167.177, 5.4.0.1169.161, 5.4.0-1169.175, 5.15.0.194.171, 5.15.0-194.204, 5.15.0.1111.111, 5.15.0-1111.112, 6.8.0-142.142+fips1, 6.8.0-142.142.1, 6.8.0-142.142.1~22.04.1, 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, 6.8.0-1066.73~22.04.1, 6.8.0-1068.76, 6.8.0-1068.76+fips1, 6.8.0-1068.76~22.04.1, 6.8.0-1069.77, 6.8.0-1069.77~22.04.1, 6.8.0-2054.56, 6.8.1-1060.61, 6.8.1-1060.61~22.04.1, 7.0.0-29.29, 7.0.0-29.29.1, 7.0.0-1009.9, 7.0.0-1010.10, 7.0.0-1011.11, 7.0.0-1016.16
linux-aws-fips (Ubuntu package) - addressed in versions 4.15.0.1152.150, 4.15.0-1152.164+1, 4.15.0.2115.111, 4.15.0-2115.121, 4.15.0.2135.129, 4.15.0-2135.141, 6.8.0-1065.68+fips1
linux-aws (Ubuntu package) - addressed in versions 4.15.0.1190.203, 4.15.0-1190.207, 4.15.0-1190.207~16.04.1, 4.15.0.1197.195, 4.15.0-1197.210, 4.15.0.2098.96, 4.15.0-2098.104, 5.15.0.194.159, 5.15.0-194.204, 5.15.0-194.204~20.04.1, 5.15.0.1079.82, 5.15.0-1079.83, 5.15.0.1099.98, 5.15.0-1099.107, 5.15.0.1108.104, 5.15.0-1108.110, 5.15.0.1108.112, 5.15.0-1108.113, 5.15.0.1110.107, 5.15.0-1110.114, 5.15.0.1111.110, 5.15.0-1111.117, 5.15.0.1112.111, 5.15.0-1112.118, 5.15.0.1113.109, 5.15.0-1113.119, 5.15.0.1115.119, 5.15.0-1115.124, 5.15.0.1116.106, 5.15.0.1116.112, 5.15.0.1116.119, 5.15.0-1116.123, 5.15.0-1116.123+fips1, 5.15.0-1116.126+fips1, 5.15.0.1117.114, 5.15.0-1117.127, 5.15.0-1121.130, 5.15.0.1122.106, 5.15.0.1122.120, 5.15.0-1122.131, 5.15.0-1122.131+fips1, 6.8.0-1065.68, 6.8.0-1065.68~22.04.1
linux-aws-hwe (Ubuntu package) - addressed in versions 4.15.0-1197.210~16.04.1, 4.15.0.1207.175, 4.15.0-1207.222, 4.15.0-1207.222~14.04.1
perf-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
python3-perf-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
python3-perf - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
python2-perf-debuginfo - update to 4.19.90-2608.6.0.0388
python2-perf - update to 4.19.90-2608.6.0.0388
perf - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-tools-devel - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-tools-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-tools - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-source - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-devel - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-debugsource - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
bpftool-debuginfo - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
bpftool - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
kernel - addressed in versions 4.19.90-2608.6.0.0388, 6.6.0-145.1.20.157
linux-bluefield (Ubuntu package) - addressed in versions 5.4.0.1123.119, 5.4.0-1123.130
linux-raspi-5.4 (Ubuntu package) - update to 5.4.0-1147.160~18.04.1
linux-fips (Ubuntu package) - addressed in versions 5.15.0.194.113, 5.15.0-194.204+fips1
linux-nvidia-tegra (Ubuntu package) - addressed in versions 5.15.0-1057.57, 5.15.0.1057.59, 5.15.0.1068.68, 5.15.0-1068.70, 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
kernel-headers - update to 6.6.0-145.1.20.157
linux-nvidia (Ubuntu package) - addressed in versions 6.8.0-1063.66, 6.8.0-1063.66.1, 6.8.0-1063.66~22.04.1, 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-29.29~24.04.2
linux-gcp (Ubuntu package) - addressed in versions 7.0.0-1005.6, 7.0.0-1010.10
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1010.10
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1010.10~24.04.1
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