Astro: Reflected/Stored XSS via unescaped <script>/<style> tag content in JSX/MDX rendering

Summary

Astro is a web framework for content-driven websites. Prior to 7.3.2, Astro's JSX and MDX rendering pipeline treats string children of script and style elements as trusted HTML without distinguishing compiler-generated literal content from dynamic expression values. An application that passes attacker-controlled data directly as a dynamic child can allow a value containing a closing script or style tag to terminate the element and inject arbitrary HTML and JavaScript. Other JSX expression contexts escape dynamic strings automatically; the issue is limited to script and style children rendered through the astro:jsx renderer, including MDX components. Successful exploitation can produce reflected or stored cross-site scripting under the application's origin. This issue is fixed in 7.3.2.

Timeline

1. Oct 21, 2026, 5:32 PM UTCCVE published
2. Oct 22, 2026, 7:20 PM UTCFirst seen by cve.now
3. Oct 23, 2026, 2:47 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

4. Oct 23, 2026, 3:11 PM UTCRecord last updated

Affected versions

• withastro astro

  fixed in 7.3.2

• astronpm

  fixed in 7.3.2

References 4