If you or your ISP are running BIG-IP devices, they are almost certainly under active attack right now. On Wednesday, F5 Networks issued patches for a remote code execution vulnerability in BIG-IP devices. Within hours, security researchers reported targeted attacks against BIG-IP devices.

BIG-IP devices are popular and control some of the most important devices on the Internet. The devices, traffic shaping systems, load balancers, firewalls, access gateways, and rate limiters, are used by 48 of the 50 Fortune 50 systems.

F5 said the vulnerability, tracked as CVE-2020-5902, could allow attackers to take full control over unpatched systems that are accessible on the internet. The vulnerability was deemed so critical that it received a 10 severity score, the maximum on the CVSSv3 severity scale. A CVSSv3 score of 10 means the vulnerability is easy to exploit, easy to automate, can be used over the internet, and doesn’t require advanced coding skills to take advantage of.

If you’re running BIG-IP equipment and you have not patched your systems, you’ve probably already lost control of your devices.