CVE-2026-114128: Astro: Reflected/Stored XSS via unescaped <script>/<style> tag content in JSX/MDX rendering

Astro’s JSX and MDX rendering pipeline treated string children of <script> and <style> elements as trusted HTML. When a dynamic value was passed through a JSX expression, such as <script>{value}</script>, an attacker-controlled value containing </script> or </style> could terminate the element and inject arbitrary HTML and JavaScript.

Other JSX expression contexts escaped dynamic strings automatically. This behavior was limited to <script> and <style> children rendered through Astro’s astro:jsx renderer, including MDX components.