For the second time in a week, security researchers have warned that extortionists exploited the critical flaw.

Such VPN software has proven a popular foothold for spies over the years.

Agencies have until Friday to report back to CISA on their level of exposure.

Vulnerabilities can come back to bite you.

CISA has increasingly used its emergency-directive authority to try to keep foreign spies or criminals from burrowing into federal networks

The episode highlights how, with thousands of software vulnerabilities released each year, some matter much more than others.

The bugs are in Citrix software that allows clients to remotely connect to corporate networks with their mobile phones.

With hackers exploiting a critical bug in its products, Citrix has expedited its timeline for patching.

A fix is on the way, the company says.

“We have a working exploit, and it took us under a day to develop it,” one security expert told CyberScoop.