CVE-2026-72055

A flaw was found in the Linux kernel's ip6_vti component, which handles IPv6 Virtual Tunnel Interfaces. A local attacker with certain network administration privileges in one isolated network environment (network namespace) could exploit this vulnerability. This allows them to modify the configuration of a tunnel in a different isolated network environment where they do not have full administrative rights, potentially leading to unauthorized network changes or the redirection of network traffic.

ip6_vti changelink authorization was checked only against dev_net(dev), while vti6_changelink can also modify a tunnel whose link namespace is t net. A caller with CAP_NET_ADMIN in the device namespace but not in the tunnel link namespace can therefore rewrite tunnel configuration across a namespace boundary when such a device is moved or created across netns. For the CVSS the PR:L is used because reliable triggering requires a local process with CAP_NET_ADMIN in one namespace, such as container root or a delegated network administration context, but not full privileges in the affected tunnel namespace. The issue is not directly network reachable because it is triggered through rtnetlink control plane operations, not by packets. Impact can include unauthorized tunnel reconfiguration, traffic disruption, and possible traffic redirection or policy bypass depending on the deployment.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.