GHSA-R3R9-WP5J-PQ5G

Vulnerability from github – Published: 2026-09-22 19:54 – Updated: 2026-09-22 19:54
VLAI
Summary
request-filtering-agent: Synchronous throw from createConnection() for literal private-IP hosts bypasses req.on('error'), crashing the Node.js process
Details

Summary

RequestFilteringHttpAgent / RequestFilteringHttpsAgent block requests to private IPs, but the blocking happens via a synchronous throw inside createConnection() for literal private-IP hostnames (e.g. 169.254.169.254, 127.0.0.1). Node.js's http.request / http.get expects createConnection to emit an error asynchronously; a synchronous throw instead escapes the caller's req.on('error', ...) handler entirely and becomes an unhandled exception that crashes the process.

Affected

request-filtering-agent <= 3.2.0 (latest).

PoC (replicated live on 3.2.0)

const http = require('http');
const { RequestFilteringHttpAgent } = require('request-filtering-agent');
const agent = new RequestFilteringHttpAgent();
process.on('uncaughtException', e => {
  console.log('CRASH:', e.message); // fires — process dies
});
const req = http.get({ hostname: '169.254.169.254', port: 80, agent });
req.on('error', e => { /* never reached for literal IPs */ });

Actual output:

request-filtering-agent@3.2.0 synchronous throw escaping error event:
UNCAUGHT EXCEPTION (process crash): DNS lookup 169.254.169.254(...) is not allowed. Because, It is private IP address.
*** CRASH CONFIRMED: createConnection throws sync, bypasses req.on("error") ***

Note: hostnames that resolve to private IPs (e.g. localhost) are handled via the async lookup path and correctly emit an error event — this asymmetry confirms the sync-throw is a defect.

Impact

Any application using request-filtering-agent where an attacker can trigger an HTTP request to a literal private-IP (e.g. from a user-supplied URL that is pre-validated but still reaches http.get) will crash the Node.js process — full DoS.

Fix

Instead of throwing synchronously in createConnection(), call callback(error) (the Node.js net.createConnection error-callback convention) or use process.nextTick(() => socket.destroy(error)) on the returned socket to emit the error asynchronously, allowing req.on('error') to handle it.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "request-filtering-agent"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-62985"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-248"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-22T19:54:18Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n`RequestFilteringHttpAgent` / `RequestFilteringHttpsAgent` block requests to private IPs, but the blocking happens via a **synchronous `throw`** inside `createConnection()` for literal private-IP hostnames (e.g. `169.254.169.254`, `127.0.0.1`). Node.js\u0027s `http.request` / `http.get` expects `createConnection` to emit an error asynchronously; a synchronous throw instead escapes the caller\u0027s `req.on(\u0027error\u0027, ...)` handler entirely and becomes an **unhandled exception** that crashes the process.\n\n### Affected\n`request-filtering-agent` \u003c= 3.2.0 (latest).\n\n### PoC (replicated live on 3.2.0)\n```js\nconst http = require(\u0027http\u0027);\nconst { RequestFilteringHttpAgent } = require(\u0027request-filtering-agent\u0027);\nconst agent = new RequestFilteringHttpAgent();\nprocess.on(\u0027uncaughtException\u0027, e =\u003e {\n  console.log(\u0027CRASH:\u0027, e.message); // fires \u2014 process dies\n});\nconst req = http.get({ hostname: \u0027169.254.169.254\u0027, port: 80, agent });\nreq.on(\u0027error\u0027, e =\u003e { /* never reached for literal IPs */ });\n```\nActual output:\n```\nrequest-filtering-agent@3.2.0 synchronous throw escaping error event:\nUNCAUGHT EXCEPTION (process crash): DNS lookup 169.254.169.254(...) is not allowed. Because, It is private IP address.\n*** CRASH CONFIRMED: createConnection throws sync, bypasses req.on(\"error\") ***\n```\nNote: hostnames that resolve to private IPs (e.g. `localhost`) are handled via the async lookup path and correctly emit an error event \u2014 this asymmetry confirms the sync-throw is a defect.\n\n### Impact\nAny application using `request-filtering-agent` where an attacker can trigger an HTTP request to a literal private-IP (e.g. from a user-supplied URL that is pre-validated but still reaches `http.get`) will crash the Node.js process \u2014 full DoS.\n\n### Fix\nInstead of throwing synchronously in `createConnection()`, call `callback(error)` (the Node.js `net.createConnection` error-callback convention) or use `process.nextTick(() =\u003e socket.destroy(error))` on the returned socket to emit the error asynchronously, allowing `req.on(\u0027error\u0027)` to handle it.",
  "id": "GHSA-r3r9-wp5j-pq5g",
  "modified": "2026-09-22T19:54:18Z",
  "published": "2026-09-22T19:54:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/azu/request-filtering-agent/security/advisories/GHSA-r3r9-wp5j-pq5g"
    },
    {
      "type": "WEB",
      "url": "https://github.com/azu/request-filtering-agent/commit/9d12561064524807fc399158eaa5bd7a40dd8cd0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/azu/request-filtering-agent"
    },
    {
      "type": "WEB",
      "url": "https://github.com/azu/request-filtering-agent/releases/tag/v3.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "request-filtering-agent: Synchronous throw from createConnection() for literal private-IP hosts bypasses req.on(\u0027error\u0027), crashing the Node.js process"
}



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