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

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

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.

Linux kernel
openEuler
Ubuntu
bpftool
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-devel
kernel-debugsource
kernel-debuginfo
bpftool-debuginfo
kernel
linux (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-aws-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
bpftool - update to 6.6.0-145.1.20.157
python3-perf-debuginfo - update to 6.6.0-145.1.20.157
python3-perf - update to 6.6.0-145.1.20.157
perf-debuginfo - update to 6.6.0-145.1.20.157
perf - update to 6.6.0-145.1.20.157
kernel-tools-devel - update to 6.6.0-145.1.20.157
kernel-tools-debuginfo - update to 6.6.0-145.1.20.157
kernel-tools - update to 6.6.0-145.1.20.157
kernel-source - update to 6.6.0-145.1.20.157
kernel-headers - update to 6.6.0-145.1.20.157
kernel-devel - update to 6.6.0-145.1.20.157
kernel-debugsource - update to 6.6.0-145.1.20.157
kernel-debuginfo - update to 6.6.0-145.1.20.157
bpftool-debuginfo - update to 6.6.0-145.1.20.157
kernel - update to 6.6.0-145.1.20.157
linux (Ubuntu package) - addressed in versions 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-hwe-7.0 (Ubuntu package) - update to 7.0.0-29.29~24.04.2
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

• https://git.kernel.org/stable/c/2abfb19bbb81958714ad1d43ebeb65b30394184b
• https://git.kernel.org/stable/c/2fc7bc087cc7085368263d9d37bfe9a0bddd6a2d
• https://git.kernel.org/stable/c/47fb3c2b4203556308e64354b3e78f2ce221d646
• https://git.kernel.org/stable/c/90fd4513315ca07da99cfd8549d3e553a7160f0d
• https://git.kernel.org/stable/c/a5c0359f5cbc51a2e2b114d6041e0f3c73f903e9
• https://git.kernel.org/stable/c/c327fa4fca31415431202e063767a7ae342e19c6
• https://git.kernel.org/stable/c/f513f308cc4bdb4530d033431592ffbc29b7fca1
• https://git.kernel.org/stable/c/fc657ac0767c49839b3ef0b08dc0953ca30883f8

• Improper input validation in Linux kernel ipv6
• openEuler 24.03 LTS SP1 update for kernel
• Ubuntu update for linux
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux-aws-7.0
• Ubuntu update for linux-hwe-7.0