CVE-2026-25545
HIGH
GHSA-qq67-mvv5-fw3g
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Lifecycle Timeline
4Tags
Description
Astro is a web framework. Prior to version 9.5.4, Server-Side Rendered pages that return an error with a prerendered custom error page (eg. `404.astro` or `500.astro`) are vulnerable to SSRF. If the `Host:` header is changed to an attacker's server, it will be fetched on `/500.html` and they can redirect this to any internal URL to read the response body through the first request. An attacker who can access the application without `Host:` header validation (eg. through finding the origin IP behind a proxy, or just by default) can fetch their own server to redirect to any internal IP. With this they can fetch cloud metadata IPs and interact with services in the internal network or localhost. For this to be vulnerable, a common feature needs to be used, with direct access to the server (no proxies). Version 9.5.4 fixes the issue.
Analysis
Astro web framework versions prior to 9.5.4 contain a server-side request forgery vulnerability in error page handling that allows unauthenticated remote attackers to bypass Host header validation and redirect requests to internal services or cloud metadata endpoints. By manipulating the Host header when accessing prerendered error pages, attackers can read response bodies from internal URLs, cloud metadata services, or localhost resources. …
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Remediation
Within 24 hours: Identify all systems running Astro framework and document current versions; enable enhanced logging on affected applications. Within 7 days: Apply vendor patch to upgrade all Astro instances to version 9.5.4 or later; conduct post-patch validation testing. …
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External POC / Exploit Code
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