GHSA-2pvr-wf23-7pc7
HIGHGHSA-2pvr-wf23-7pc7 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in astro. O3 Security confirms whether GHSA-2pvr-wf23-7pc7 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Astro: Host header SSRF in prerendered error page fetch
Real-World Exposure
astroReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
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.
Who is affected
This affects SSR deployments that:
- Have a prerendered 404 or 500 page
- Use
createRequestFromNodeRequestfromastro/app/nodewithapp.render()without overridingprerenderedErrorPageFetch— this includes custom servers built on the public API and third-party adapters
Not affected:
@astrojs/node>= 9.5.4 (reads error pages from disk)@astrojs/cloudflare(uses the ASSETS binding)- The dev server (renders error pages in-process)
How it works
createRequestFromNodeRequest builds request.url from the raw Host / :authority header. The allowedDomains option is accepted but only gates X-Forwarded-For — it does not constrain the URL origin. (The public createRequest does fall back to localhost for unvalidated hosts; this internal builder did not.)
When app.render() encounters a 404 or 500 with a prerendered error route, default-handler.ts constructs the error page URL using the origin from request.url and fetches it via prerenderedErrorPageFetch, which defaults to global fetch. The response body is served to the client.
An attacker sends a request with Host: attacker-host:port, triggers an error (e.g., requesting a nonexistent path for a 404), and receives the response from the attacker-controlled host reflected back.
Remediation
The error page fetch origin is now validated against allowedDomains before use. When the host is validated, the original origin is preserved. Otherwise, it falls back to localhost. The fetch is also wrapped in a try/catch so that connection failures degrade gracefully to a plain error response.
Credit
5ud0 / Tarmo Technologies
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | astro | all versions | 6.4.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for astro. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update astro to 6.4.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2pvr-wf23-7pc7 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2pvr-wf23-7pc7 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2pvr-wf23-7pc7. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2pvr-wf23-7pc7 in your dependencies?
O3 detects GHSA-2pvr-wf23-7pc7 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.