CVE-2026-59727

CVE-2026-59727 · Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands

This page contains facts from public vulnerability sources. Check the original advisory before updating.

Astro is a web framework for content-driven websites. In versions 3.10.0 through 7.0.3, when a transition:persist, transition:scope, or transition:persist-props directive is applied to a client-hydrated (client:*) component, Astro copied the directive value onto the rendered <astro-island> element without HTML-escaping it. If a developer reflects attacker-controlled input into one of these directives, an attacker can break out of the attribute and inject arbitrary HTML/JavaScript into the server-rendered output, resulting in reflected cross-site scripting (XSS). Exploitation requires the application developer to have written a non-idiomatic pattern — passing untrusted, request-derived input directly into a transition directive. Astro applications that do not route untrusted input into these directives are unaffected. This issue has been fixed in version 7.0.4.

CVSS 2.1 · Low · EPSS 0.5% · Fix available

Published

2026-07-27T19:42:32.222Z

Updated

2026-07-28T15:20:18.915Z

Stack: node

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