Cross-site Scripting vulnerability due to improper use of string.replace in dom-expressions

Summary

dom-expressions is a Fine-Grained Runtime for Performant DOM Rendering. In affected versions the use of javascript's `.replace()` opens up to potential Cross-site Scripting (XSS) vulnerabilities with the special replacement patterns beginning with `$`. Particularly, when the attributes of `Meta` tag from solid-meta are user-defined, attackers can utilise the special replacement patterns, either `$'` or `$\`` to achieve XSS. The solid-meta package has this issue since it uses `useAffect` and context providers, which injects the used assets in the html header. "dom-expressions" uses `.replace()` to insert the assets, which is vulnerable to the special replacement patterns listed above. This effectively means that if the attributes of an asset tag contained user-controlled data, it would be vulnerable to XSS. For instance, there might be meta tags for the open graph protocol in a user profile page, but if attackers set the user query to some payload abusing `.replace()`, then they could execute arbitrary javascript in the victim's web browser. Moreover, it could be stored and cause more problems. This issue has been addressed in version 0.39.5 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Timeline

1. Feb 21, 2025, 9:09 PM UTCCVE published
2. Feb 24, 2025, 2:47 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Feb 24, 2025, 2:47 PM UTCRecord last updated

Affected versions

• ryansolid dom-expressions

  fixed in 0.39.5

• dom-expressionsnpm

  fixed in 0.39.5

References 2