arrayLimit bypass in bracket notation allows DoS via memory exhaustion

{
  "id": "5ab8c9e8923e09d00fd8329ce62b2f413b95fa0938cab7a51a7f7a2c435ec077",
  "url": "https://osv.dev/vulnerability/CVE-2025-15284",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "arrayLimit bypass in bracket notation allows DoS via memory exhaustion",
    "summary": "Improper Input Validation vulnerability in qs (parse modules) allows HTTP DoS.This issue affects qs: < 6.14.1. Summary The arrayLimit option in qs did not enforce limits for bracket notation (a[]=1&a[]=2), only for indexed notation (a[0]=1). This is a consistency bug; arrayLimit should apply uniformly across all array notations. Note: The default parameterLimit of 1000 effectively mitigates the DoS scenario originally described. With default options, bracket notation cannot produce arrays larger than parameterLimit regardless of arrayLimit, because each a[]=valueconsumes one parameter slot. The severity has been reduced accordingly. Details The arrayLimit option only checked limits for indexed notation (a[0]=1&a[1]=2) but did not enforce it for bracket notation (a[]=1&a[]=2). Vulnerable code (lib/parse.js:159-162): if (root === '[]' && options.parseArrays) { obj = utils.combine([], leaf); // No arrayLimit check } Working code (lib/parse.js:175): else if (index <= options.arrayLimit) { // Limit checked here obj = []; obj[index] = leaf; } The bracket notation handler at line 159 uses utils.combine([], leaf) without validating against options.arrayLimit, while indexed notation at line 175 checks index <= options.arrayLimit before creating arrays. PoC const qs = require('qs'); const result = qs.parse('a[]=1&a[]=2&a[]=3&a[]=4&a[]=5&a[]=6', { arrayLimit: 5 }); console.log(result.a.length); // Output: 6 (should be max 5) Note on parameterLimit interaction: The original advisory's \"D",
    "evidence": "osv:CVE-2025-15284",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-15284",
      "aliases": [
        "CVE-2025-15284",
        "GHSA-6rw7-vpxm-498p"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ljharb/qs",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3fa11a5f643c76896387bd2d86904a2d0141fdf7"
                },
                {
                  "fixed": "3086902ecf7f088d0d1803887643ac6c03d415b9"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:qs_project:qs:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "6.14.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "3086902ecf7f088d0d1803887643ac6c03d415b9"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v6.10.5",
            "v6.11.2",
            "v6.12.3",
            "v6.13.1",
            "v6.14.0",
            "v6.13.0",
            "v6.12.2",
            "v6.12.1",
            "v6.12.0",
            "v6.11.1",
            "v6.11.0",
            "v6.10.4",
            "v6.10.3",
            "v6.10.2",
            "v6.10.1",
            "v6.10.0",
            "v6.9.6",
            "v6.9.5",
            "v6.9.4",
            "v6.9.3",
            "v6.9.2",
            "v6.9.1",
            "v6.9.0",
            "v6.8.0",
            "v6.7.0",
            "v6.6.0",
            "v6.5.2",
            "v6.4.0",
            "v6.5.1",
            "v6.5.0",
            "v6.3.1",
            "v6.1.0",
            "v6.2.1",
            "v6.3.0",
            "v5.2.0",
            "v6.2.0",
            "v6.0.2",
            "v6.0.1",
            "v6.0.0",
            "v5.1.0",
            "v5.0.0",
            "v4.0.0",
            "v3.1.0",
            "v3.0.0",
            "v2.4.2",
            "v2.4.1",
            "v2.4.0",
            "v2.3.3",
            "v2.3.2",
            "v2.3.1",
            "v2.3.0",
            "v2.2.5",
            "v2.2.4",
            "v2.2.3",
            "v2.2.2",
            "v2.2.1",
            "v2.2.0",
            "v2.1.0",
            "v2.0.0",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.1.0",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-15284.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.045541279Z",
      "provider": "osv",
      "references": [
        "https://npmjs.com/qs",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/15xxx/CVE-2025-15284.json",
        "https://github.com/ljharb/qs/security/advisories/GHSA-6rw7-vpxm-498p",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-15284",
        "https://github.com/ljharb/qs/commit/3086902ecf7f088d0d1803887643ac6c03d415b9",
        "https://github.com/ljharb/qs"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20"
        ],
        "cna_assigner": "harborist",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/15xxx/CVE-2025-15284.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-15284",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517328,
  "published_at": "2025-12-29T22:56:45.24+00:00"
}