F5 discloses breach tied to nation-state threat actor

F5 disclosed on Wednesday that it had been the target of a “highly sophisticated” cyberattack attributed to a nation-state actor. According to an 8-K form filed with the Securities and Exchange Commission, the company first became aware of unauthorised access on 9 August 2025 and began standard incident response measures, including enlisting external cybersecurity consultants.

The Department of Justice authorised F5 to delay public disclosure of the breach under Item 1.05(c) of Form 8-K due to ongoing law enforcement considerations, with the government allowing the delay if a breach is determined to be a substantial risk to national security or public safety. Investigators also found that the threat actor maintained prolonged access to parts of F5’s infrastructure.

The disclosure follows the DOJ’s guidance and underscores the firm’s view of the incident as a serious security event tied to a nation-state threat actor.