CVE-2026-53221

In the Linux kernel, the following vulnerability has been resolved:

ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()

In vti6_tnl_lookup(), when an exact match for a tunnel fails,
the code falls back to searching for wildcard tunnels:

- Tunnels matching the packet's local address, with any remote address
  wildcard remote).

- Tunnels matching the packet's remote address, with any local address
  (wildcard local).

However, vti6 stores all these different types of tunnels in the same
hash table (ip6n->tnls_r_l) prone to hash collisions.

The bug is that the fallback search loops in vti6_tnl_lookup() were
missing checks to ensure that the candidate tunnel actually has
a wildcard address.