Ohai Chefs!
I just released Chef Zero 1.6.3. There's a 99% probability this won't affect you, since the latest stable is 2.0 and the version in Chef Client in 1.7. However, there was a critical bug that affects Chef Client < 11.8 with respect to JSON parsing. This has been fixed in 1.7 and 2.0 for some time, but was never backported to the 1.6 series.
https://github.com/opscode/chef-zero/compare/v1.6.2...v1.6.3
If you are using Chef Client 11.10 you can disregard this release :).
Happy testing!
Seth Vargo
Release Engineer, Chef
@sethvargo