CVE-2026-64043 ovpn: fix race between deleting interface and adding new peer

Medium 4.7 Published 19 Jul 2026 Updated 19 Jul 2026

A race condition in the Linux kernel OVPN module allows a local attacker to cause a denial of service by hanging the network device during interface deletion.

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-2026-64043?

CVE-2026-64043 is a medium-severity vulnerability in Linux kernel, published on 19 Jul 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:

ovpn: fix race between deleting interface and adding new peer

While deleting an existing ovpn interface, there is a very narrow window where adding a new peer via netlink may cause the netdevice to hang and prevent its unregistration.

It may happen during ovpn_dellink(), when all existing peers are freed and the device is queued for deregistration, but a CMD_PEER_NEW message comes in adding a new peer that takes again a reference to the netdev.

At this point there is no way to release the device because we are under the assumption that all peers were already released.

Fix the race condition by releasing all peers in ndo_uninit(), when the netdevice has already been removed from the netdev list.

Also ovpn_peer_add() has now an extra check that forces the function to bail out if the device reg_state is not REGISTERED. This way any incoming CMD_PEER_NEW racing with the interface deletion routine will simply stop before adding the peer.

Note that the above check happens while holding the netdev_lock to prevent racing netdev state changes.

ovpn_dellink() is now empty and can be removed.

Weakness: CWE-362

Which versions are affected by CVE-2026-64043?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64043?

Apply the vendor's patch.

Is CVE-2026-64043 being exploited?

There is no known exploitation of CVE-2026-64043 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-64043, DEBIAN-CVE-2026-64043, GHSA-74fm-4xxg-774p, UBUNTU-CVE-2026-64043.