CVE-2026-41067 Astro: XSS via incomplete `</script>` sanitization in `define:vars` allows case-insensitive and whitespace-based bypass
Attackers can bypass script sanitization in Astro's define:vars directive to inject arbitrary JavaScript, enabling cross-site scripting attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-41067?
CVE-2026-41067 is a medium-severity cross-site scripting vulnerability in withastro astro, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Astro is a web framework. Prior to 6.1.6, the defineScriptVars function in Astro's server-side rendering pipeline uses a case-sensitive regex /<\/script>/g to sanitize values injected into inline <script> tags via the define:vars directive. HTML parsers close <script> elements case-insensitively and also accept whitespace or / before the closing >, allowing an attacker to bypass the sanitization with payloads like </Script>, </script >, or </script/> and inject arbitrary HTML/JavaScript. This vulnerability is fixed in 6.1.6.
Weakness: CWE-79
Which versions are affected by CVE-2026-41067?
2 open source packages ship an affected version, including astro. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
astro npm | All versions | 6.1.6 |
astro npm | All versions | 6.1.6 |
Products include Astro Astro.
How do I fix CVE-2026-41067?
Upgrade astro to 6.1.6 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-41067 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41067 exists.
Other vulnerabilities in withastro astro
- CVE-2024-56159 Server source code is exposed to the public if sourcemaps are enabled
- CVE-2026-54299 Astro: Host header SSRF in prerendered error page fetch
- CVE-2025-59837 astro allows bypass of image proxy domain validation leading to SSRF and potential XSS
- CVE-2026-50146 Astro: Reflected XSS via unescaped slot name
- CVE-2025-64764 Astro is vulnerable to Reflected XSS via the server islands feature
Sources
Also known as GHSA-j687-52p2-xcff.