CVE-2026-54299 Astro: Host header SSRF in prerendered error page fetch
Attackers can exploit unvalidated Host headers in Astro SSR apps with prerendered error pages to perform Server-Side Request Forgery and read arbitrary responses.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54299?
CVE-2026-54299 is a high-severity server-side request forgery vulnerability in withastro astro, published on 22 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Astro is a web framework. Prior to 6.4.6, Astro SSR apps with prerendered error pages (/404 or /500 using export const prerender = true) fetch those pages over HTTP at runtime when an error occurs. The URL for this fetch is derived from request.url, which in turn gets its origin from the incoming Host header. When the Host header is not validated against allowedDomains, an attacker can point the fetch at an arbitrary host and read the response. This vulnerability is fixed in 6.4.6.
Which versions are affected by CVE-2026-54299?
2 open source packages ship an affected version, including astro. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
astro npm | All versions | 6.4.6 |
astro npm | All versions | 6.4.6 |
Products include Astro Astro.
How do I fix CVE-2026-54299?
Upgrade astro to 6.4.6 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-54299 being exploited?
There is no known exploitation of CVE-2026-54299 in the wild and no public exploit code.
Other vulnerabilities in withastro astro
- CVE-2024-56159 Server source code is exposed to the public if sourcemaps are enabled
- 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
- CVE-2025-64765 Astro middleware authentication checks based on url.pathname can be bypassed via url encoded values
Sources
Also known as GHSA-2pvr-wf23-7pc7.