Foster, who was brought into the All Blacks coaching group by Head Coach Steve Hansen in 2012, said: "I've really enjoyed the last five years, the successes and challenges we've had as a team, and the progress we've made, so it was a natural decision for me to sign on and commit through to the next World Cup."
Cron added: "While our eyes are currently on the upcoming DHL New Zealand Lions Series, it's exciting to think the next Rugby World Cup is on the horizon. It'll be my fifth World Cup (four with the All Blacks and one with Wales) so that'll be something to look forward to. But more than anything, I'm looking forward to helping the team grow over the next two years to get ready for that."
All Blacks Head Coach Steve Hansen has also praised his two fellow coaches.
"Having 'Fosie' re-sign is great news. He's been an integral member of the All Blacks coaching and management group over the last five years and he brings a lot of composure, rugby nous and intellect to the team.
"He's a key member of our management leadership team, he runs the coaching unit and has done a fantastic job in that regard. To know that he's continuing through to the end of the Rugby World Cup in 2019 is fantastic."
Hansen described Cron as a "master craftsman."