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EUVD-2026-270970

fkie_cve-2026-27729

Astro is a web framework. In versions 9.0.0 through 9.5.3, Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments. On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server. Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop. Action names are discoverable from HTML form attributes on any public page, so no authentication is required. The vulnerability allows unauthenticated denial of service against SSR standalone deployments using server actions. A single oversized request crashes the server process, and repeated requests cause a persistent crash-restart loop in containerized environments. Version 9.5.4 contains a fix.

GHSA-jm64-8m5q-4qh8 — Astro has memory exhaustion DoS due to missing request body size limit in Server Actions

Affected: npm: @astrojs/node

## Summary

Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments.

## Details

On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server.

Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop.

Action names are discoverable from HTML form attributes on any public page, so no authentication is required.

## PoC

### Setup

Create a new Astro project with the following files:

`package.json`: ```json { "name": "poc-dos", "private": true, "scripts": { "build": "astro build", "start:128mb": "node --max-old-space-size=128 dist/server/entry.mjs" }, "dependencies": { "astro": "5.17.2", "@astrojs/node": "9.5.3" } } ```

`astro.config.mjs`: ```javascript import { defineConfig } from 'astro/config'; import node from '@astrojs/node';

export default defineConfig({ output: 'server', adapter: node({ mode: 'standalone' }), }); ```

`src/actions/index.ts`: ```typescript import { de…