U.S. cybersecurity company F5 fell 12% on Thursday after disclosing a system breach in which a "highly sophisticated nation-state threat actor" gained long-term access to some systems.
F5 shares were pacing for the worst day since April 27, 2022, when the stock fell 12.8%.
The company disclosed the breach in a Securities and Exchange Commission filing on Wednesday and said the hack affected its BIG-IP product development environment. F5 said the attacker infiltrated files containing some source code and information on "undisclosed vulnerabilities" in BIG-IP.
The breach was later attributed to state-backed hackers from China, Bloomberg reported, citing people familiar with the matter.
F5, which was made aware of the attack in August, said they have not seen evidence of any new unauthorized activity.