# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-2pvr-wf23-7pc7

## 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.

Weakness: CWE-918 (Server-Side Request Forgery), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-54299?

2 open source packages ship an affected version, including astro. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `astro` | npm | All versions | 6.4.6 |
| `astro` | npm | All versions | 6.4.6 |

Products: Astro Astro.

## How do I fix CVE-2026-54299?

Upgrade astro to 6.4.6 or later.

## 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](https://insights.sbomify.com/CVE-2024-56159/): Server source code is exposed to the public if sourcemaps are enabled (high 7.8)
- [CVE-2025-59837](https://insights.sbomify.com/CVE-2025-59837/): astro allows bypass of image proxy domain validation leading to SSRF and potential XSS (high 7.2)
- [CVE-2026-50146](https://insights.sbomify.com/CVE-2026-50146/): Astro: Reflected XSS via unescaped slot name (high 7.1)
- [CVE-2025-64764](https://insights.sbomify.com/CVE-2025-64764/): Astro is vulnerable to Reflected XSS via the server islands feature (high 7.1)
- [CVE-2025-64765](https://insights.sbomify.com/CVE-2025-64765/): Astro middleware authentication checks based on url.pathname can be bypassed via url encoded values (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54299 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-54299 in the wild and no public exploit code.

Affected packages and fixed versions:
- astro (npm): affected all versions; fixed in 6.4.6
- astro (npm): affected all versions; fixed in 6.4.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54299/ (Markdown: https://insights.sbomify.com/CVE-2026-54299/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54299
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54299
- OSV: https://osv.dev/vulnerability/CVE-2026-54299

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54299/
Summaries are generated and may contain mistakes; the official description above is the record.