Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-05-08T00:00:00 kernel: netfilter: flowtable: strictly check for maximum number of actions 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CWE-770

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: strictly check for maximum number of actions The maximum number of flowtable hardware offload actions in IPv6 is: * ethernet mangling (4 payload actions, 2 for each ethernet address) * SNAT (4 payload actions) * DNAT (4 payload actions) * Double VLAN (4 vlan actions, 2 for popping vlan, and 2 for pushing) for QinQ. * Redirect (1 action) Which makes 17, while the maximum is 16. But act_ct supports for tunnels actions too. Note that payload action operates at 32-bit word level, so mangling an IPv6 address takes 4 payload actions. Update flow_action_entry_next() calls to check for the maximum number of supported actions. While at it, rise the maximum number of actions per flow from 16 to 24 so this works fine with IPv6 setups.

A flaw was found in the Netfilter flowtable component of the Linux kernel. This vulnerability occurs because the system does not strictly check the maximum number of hardware offload actions for IPv6, allowing it to process more actions than supported. This could potentially lead to system instability or a denial of service (DoS) condition, where the affected system becomes unresponsive.

Red Hat Enterprise Linux 10 2026-06-04T00:00:00Z RHSA-2026:23329 kernel-0:6.12.0-211.20.1.el10_2 Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Affected kernel Red Hat Enterprise Linux 8 Affected kernel-rt Red Hat Enterprise Linux 9 Affected kernel Red Hat Enterprise Linux 9 Affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-43329 https://nvd.nist.gov/vuln/detail/CVE-2026-43329 https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-43329.mbox