Handlebars: JavaScript Injection via Unsafe Inline Embedding of Precompiled Templates

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars.precompile() uses quotedString() in lib/handlebars/compiler/code-gen.js to emit static template text into generated JavaScript without escaping sequences that terminate an enclosing HTML script element. When an application precompiles attacker-controlled template text and embeds the generated source directly in an inline script element, a closing script delimiter can end the element and cause following attacker-controlled markup to be parsed and executed. Ordinary server-side rendering and precompiled templates served as external JavaScript files are not affected. This issue is fixed in version 4.7.10.

[ Fixes ]Fixes and patches

• handlebars 4.7.10Fixed version · GitHub Advisories · npm package handlebars: upgrade to 4.7.10 or later (affected >= 4.0.0, <= 4.7.9)

[ Packages ]Affected open-source packages

• handlebars npmAffected >= 4.0.0, <= 4.7.9 · fixed in 4.7.10 · GHSA-xw65-4hp5-5hc7

[ References ]References

• github.com/handlebars-lang/handlebars.js/commit/609d1b11c833c9a3e00f56f2f34d22f425446725
• github.com/handlebars-lang/handlebars.js/pull/2185
• github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10
• github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xw65-4hp5-5hc7