Zyxel firewalls are under active cyberattack after a critical security vulnerability was disclosed last week that could allow unauthenticated, remote arbitrary code execution.

The bug (CVE-2022-30525, CVSS 9.8) was silently patched in April, but no public disclosure was made until last Thursday, May 12, when Rapid7 released a technical report on the issue. It also debuted a working proof-of-concept exploit that clearly snagged the attention of the bad-actor set: Just one day later, in-the-wild attacks started.