# CVE-2026-25545: Astro Server-Side Rendering SSRF via Host header injection

Source: https://junglewise.ai/threats/cve-2026-25545-astro-server-side-rendering-ssrf-via-host-header-injection  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-23. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-25545 · Severity: low · CVSS 3.1 · Published 2026-02-23

Astro is a modern web framework used to build and deploy websites and applications. When a server-side rendered page encounters an error and displays a custom error page (like a 404 or 500 error), an attacker can manipulate the Host header to trick the application into fetching content from the attacker's server and then following a redirect to read sensitive data from internal services. This allows attackers to access metadata services, internal databases, or other resources that should only be accessible within the organization's network.

Technologies: [@astrojs/node (npm)](https://junglewise.ai/threats/technologies/astrojs-node). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-25545 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-25545 being exploited in the wild.

**How severe is CVE-2026-25545?** Low severity, with a CVSS score of 3.1, published 23 February 2026.

**Which products and versions are affected?** @astrojs/node (npm) SEMVER:introduced=0,fixed=9.5.4.

**Is there a fix for CVE-2026-25545?** Yes. @astrojs/node (npm): upgrade to 9.5.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-25545 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-25545?** Check whether you run @astrojs/node (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- @astrojs/node (npm): upgrade to 9.5.4 or later

  ```sh
  npm install @astrojs/node@9.5.4
  ```


## Technical details

The vulnerability is a Server-Side Request Forgery (SSRF) in the error rendering logic of Astro's Node.js adapter. The vulnerable code in base.ts (line 534) fetches a prerendered error page (e.g., /500.html) using the Host header value without proper validation, and follows HTTP redirects. An attacker can set the Host header to point to their own server (e.g., "attacker.tld"), causing Astro to fetch http://attacker.tld/500.html. The attacker's server can then respond with a redirect to any internal URL (e.g., http://localhost:8000/ssrf.txt or cloud metadata endpoints), and the response body is returned to the client. The vulnerability requires direct network access to the application (bypassing any proxy that validates the Host header) and affects only server-side rendered pages with custom prerendered error pages. The patch is available in version 9.5.4 and later of @astrojs/node.

## Affected products

- Astro @astrojs/node before 9.5.4

## Identifiers

- CVE-2026-25545
- GHSA-qq67-mvv5-fw3g

## Timeline

- 2026-02-23: disclosed
- 2026-02-23: patched: Fix available in @astrojs/node 9.5.4

## References

- [https://github.com/withastro/astro/security/advisories/GHSA-qq67-mvv5-fw3g](https://github.com/withastro/astro/security/advisories/GHSA-qq67-mvv5-fw3g)

## Related threats

- [Astro Node adapter denial of service in Host header parsing](https://junglewise.ai/threats/cve-2026-102984-astro-is-a-web-framework-for-content-driven-websites-prior-to-11)
- [withastro Astro open redirect in @astrojs/node server](https://junglewise.ai/threats/cve-2026-59730-withastro-astro-open-redirect-in-astrojs-node-server)
- [Astro: Cache Poisoning due to incorrect error handling when if-match header is malformed](https://junglewise.ai/threats/cve-2026-41322-astro-cache-poisoning-due-to-incorrect-error-handling-when-if)
- [Astro Server Islands memory exhaustion DoS due to missing request body size limit](https://junglewise.ai/threats/cve-2026-29772-astro-astrojs-node-memory-exhaustion-dos-in-server-islands)
- [Astro memory exhaustion DoS in Server Actions](https://junglewise.ai/threats/cve-2026-27729-astro-memory-exhaustion-dos-in-server-actions)