Cisco Systems has been forced to issue security fixes in some of the optical networking systems it sells to service providers and telecommunications companies.
The flaws could potentially allow remote attackers to more easily target service providers with denial of service attacks (DoS), which could lead to service outages for customers.
Cisco has issued fixes for its Cisco Optical Networking System 15000 Series platform and Cisco Transport Controller, and for its Cisco 11500 Content Services Switch.
As well as the DoS threat, the bugs also posed multiple other threats, said Cisco.
The French Security Incident Response Team (FrSIRT), a security research operation, said the optical networking and transport controller bugs are critical, while the content switch vulnerability is a low-risk threat.
The 11500 Content Services Switch is designed to allow service providers to more easily deliver content to users via the web.