Description

LiquidJS is a Shopify/GitHub Pages compatible template engine written in pure JavaScript. Versions 10.25.7 and below are vulnerable to XSS through a flaw in the strip_html filter logic. The strip_html filter is intended to remove HTML tags from a string before rendering, and is widely used as an XSS sanitizer. The implementation uses a regex whose catch-all branch (<.*?>) does not match line terminators, so any HTML tag containing a \n or \r character passes through unmodified. An attacker who can place a newline inside a tag (e.g. <img\nsrc=x\nonerror=alert(1)>) bypasses sanitization entirely, since browsers treat newlines as whitespace within a tag and execute the resulting onerror/onload/etc. handler. Exploitation is possible for applications that both render attacker-controlled strings via {{ x | strip_html }} to defend against HTML injection and do not separately HTML-escape that output (default behavior — outputEscape is unset by default). This issue has been fixed in version 10.26.0.

Weaknesses 1

References 3

• github.com https://github.com/harttle/liquidjs/commit/26ea2856c7a90aec892b98d94a9b7a3e18539045
• github.com https://github.com/harttle/liquidjs/releases/tag/v10.26.0
• github.com https://github.com/harttle/liquidjs/security/advisories/GHSA-2qv6-9wx5-cwv4

Remediation