Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-06-25T00:00:00 kernel: ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup() 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-1289

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.

A flaw was found in the Linux kernel, specifically within the `ip6_vti` component responsible for managing IPv6 tunnels. This vulnerability arises from an error in the `vti6_tnl_lookup()` function, which incorrectly matches network tunnels by failing to properly verify wildcard addresses during fallback searches. This can lead to network traffic being misdirected or dropped, potentially disrupting network services. The underlying cause is a lack of checks to confirm that a candidate tunnel indeed has a wildcard address.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Fix deferred kernel Red Hat Enterprise Linux 7 Fix deferred kernel-rt Red Hat Enterprise Linux 8 Fix deferred kernel Red Hat Enterprise Linux 8 Fix deferred kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-53221 https://nvd.nist.gov/vuln/detail/CVE-2026-53221 https://lore.kernel.org/linux-cve-announce/2026062506-CVE-2026-53221-a644@gregkh/T