The security incident, first identified on Aug. 9, 2025, involved unauthorized access to some of F5’s development and engineering environments.
F5 Inc. (FFIV) on Wednesday confirmed that a sophisticated cyberattack linked to a nation-state actor breached parts of its internal systems in August.
In a U.S. Securities and Exchange Commission (SEC) filing, F5 said that it took immediate steps to contain the intrusion and brought in external cybersecurity specialists to assist with the response and investigation.
The security incident, first identified on August 9, 2025, involved unauthorized access to some of the company’s development and engineering environments. F5 stated that its containment measures have been effective so far, with no signs of further malicious activity since they were put in place.
F5 stock traded over 4% lower on Wednesday afternoon. On Stocktwits, retail sentiment around the stock shifted to ‘neutral’ from ‘bearish’ territory the previous day. Message volume improved to ‘normal’ from ‘low’ levels in 24 hours.
According to F5, the attackers were able to maintain a persistent presence in specific systems, including the BIG-IP product development environment and engineering knowledge management platform. During this time, some files were stolen, including portions of the BIG-IP source code and data about unreleased security vulnerabilities the company was working to address.
“We have no evidence of modification to our software supply chain, including our source code and our build and release pipelines,” the company added.
F5 stated that it has not faced any significant operational disruptions and is evaluating potential financial effects from the incident. The company focuses on protecting and managing applications across multiple cloud platforms. It provides services for online fraud prevention, network security, and access control.
F5 stock has gained over 30% in 2025 and over 51% in the last 12 months.
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