Disallows calls to the helperMissing-helpers (#1558) didn't solve all the problem and another exploit was reported.

The exploit will be released well after the fix is in place to give people a chance to update.

Before filing issues, please check the following points first:

• Please don't open issues for security issues. Instead, file a report at https://www.npmjs.com/advisories/report?package=handlebars
• Have a look at https://github.com/wycats/handlebars.js/blob/master/CONTRIBUTING.md
• Read the FAQ at https://github.com/wycats/handlebars.js/blob/master/FAQ.md
• Use the jsfiddle-template at https://jsfiddle.net/4nbwjaqz/4/ to reproduce problems or bugs

This will probably help you to get a solution faster.
For bugs, it would be great to have a PR with a failing test-case.