All these could shut down devices and slow transmission of data across the Internet.
In some cases, they could also allow hackers to execute code and hijack a unit, NISCC warned.
Large companies with small branch offices use IPsec to securely connect their smaller offices to headquarters.
Remote workers also use the technology to access their companies' internal networks.
It did not mention the possibility of the equipment being taken over by an intruder.
The Openswan Project, which is IPsec software used on many Linux products, is also affected.
The organization behind the software released Openswan 2.4.2 in response to the advisory.
The update can be downloaded from itsWeb site.
IBM and Microsoft said their products are not affected.
A fulllist of companies that have respondedto the alert can be found on the NISCC Web site.
