On October 15, 2025, F5 filed a Current Report on Form 8-K, in which F5 had learned in early August that a “highly sophisticated nation-state threat actor had gained unauthorized access to certain [F5] systems.” In addition, F5 stated that “during the course of its investigation, [F5] determined that the threat actor maintained long-term, persistent access to certain F5 systems, including the BIG-IP product development environment and engineering knowledge management platform,” and that “through this access, certain files were exfiltrated, some of which contained certain portions of the [F5]’s BIG-IP source code and information about undisclosed vulnerabilities that it was working on in BIG-IP.”
On this news, F5’s stock price fell $35.40 per share, or 10.7%, to close at $295.35 per share on October 16, 2025.
