Versions of handlebars prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects' __proto__ and __defineGetter__ properties, which may allow an attacker to execute arbitrary code through crafted payloads.

Recommendation

Upgrade to version 3.0.8, 4.3.0 or later.

References

• https://nvd.nist.gov/vuln/detail/CVE-2019-19919
• https://www.npmjs.com/advisories/1164
• handlebars-lang/handlebars.js#1558
• handlebars-lang/handlebars.js@2078c72
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19919