CVE-2026-43329 netfilter: flowtable: strictly check for maximum number of actions
A missing bounds check in Linux kernel netfilter flowtable allows attackers to trigger an integer overflow, potentially causing denial of service or code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43329?
CVE-2026-43329 is a high-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-43329?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43329?
Apply the vendor's patch.
Is CVE-2026-43329 being exploited?
There is no known exploitation of CVE-2026-43329 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43329, DEBIAN-CVE-2026-43329, GHSA-45q4-4828-537r, ROOT-OS-DEBIAN-11-CVE-2026-43329, ROOT-OS-UBUNTU-2204-CVE-2026-43329, ROOT-OS-UBUNTU-2404-CVE-2026-43329 and 1 more.