"HP's privacy and security policies are quite clear: we do not knowingly develop products to include security vulnerabilities," HP said in a statement.
Juniper Networks released a statement which said it was not aware of any so-called 'BIOS implants' in its products and that it had not assisted any organisation or individual in the creation of such implants.
"Juniper maintains a Secure Development Lifecycle, and it is against Juniper policy to intentionally include 'back doors' that would potentially compromise our products or put our customers at risk," it said.
"We take allegations of this nature very seriously and are working actively to address any possible exploit paths.
Cisco's chief security officer John Stewart denied any collusion with the NSA.
In a blog post he said Cisco was deeply concerned with anything that may impact the integrity of its products or its customers' networks and would continue to seek additional information,"
"At this time, we do not know of any new product vulnerabilities, and will continue to pursue all avenues to determine if we need to address any new issues.
"We do not work with any government to weaken our products for exploitation, nor to implement any so-called security 'back doors' in our products."
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