{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "v6.14.2"
              },
              {
                "fixed": "v6.15.3"
              },
              {
                "introduced": "6.7.x"
              },
              {
                "fixed": "6.13.x"
              },
              {
                "introduced": "0"
              },
              {
                "fixed": "6.7.0"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "bdcf0c7f82387c18ac8fabfccd2f440645cef47b"
            },
            {
              "fixed": "18d085e919dae70c8f1b200ab99323058edab2c2"
            },
            {
              "introduced": "125e103b61f2bef245970f5a2a8dceffe5aab59a"
            },
            {
              "fixed": "5cf516c0dd557d85d5f18d4a916c96cd9cfc2305"
            },
            {
              "introduced": "0"
            },
            {
              "fixed": "125e103b61f2bef245970f5a2a8dceffe5aab59a"
            },
            {
              "fixed": "8859c37470e11b42b547b275e4e9bd0bc8cc5464"
            }
          ],
          "repo": "https://github.com/ljharb/qs",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "harborist",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82562.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "6.14.2"
          },
          {
            "fixed": "6.16.0"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "### Summary\n\n\n\nWhen `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover.\n\n\n\n### Details\n\n\n\nIn `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained.\n\n\n\n#### PoC\n\n\n\n```js\n\n\n\nvar qs = require('qs');\n\n\n\nvar options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true };\n\n\n\nqs.parse('a=1,2,3,4', options);   // RangeError: Array limit exceeded. Only 3 elements allowed in an array.\n\n\n\nqs.parse('a[]=1,2,3,4', options); // { a: [ [ '1', '2', '3', '4' ] ] }  (no throw)\n\n\n\nqs.parse('a[]=' + '1,'.repeat(1000000) + '1', { comma: true, arrayLimit: 20, throwOnLimitExceeded: true });\n\n\n\n// no throw; a 1,000,001-element inner array is allocated\n\n\n\n```\n\n\n\n#### Fix\n\n\n\n`lib/parse.js`, applied in 8859c37 on `main` and released as v6.16.0: the `isFlatArrayValue` gate is removed, so every comma-split value is counted against `arrayLimit` before splitting regardless of key form. An in-limit group under `a[]=` still counts as one element of the outer array, and the default (`throwOnLimitExceeded: false`) path is unchanged.\n\n\n\n### Affected versions\n\n\n\n`\u003e=6.14.2 \u003c6.16.0`, fixed in v6.16.0.\n\n\n\nv6.14.2 introduced `arrayLimit` enforcement for comma values (the fix for CVE-2026-2391) but only for values not under a `[]=` key, and every release from v6.14.2 through v6.15.3 has the same gap. v6.14.0 and v6.14.1, where `throwOnLimitExceeded` exists but does not apply to any comma form, are covered by CVE-2026-2391 rather than this record. Earlier lines (6.7.x through 6.13.x) have `comma` but no `throwOnLimitExceeded`, so there is no hard cap on any comma path to bypass; releases before 6.7.0 have no `comma` option.\n\n\n\n### Impact\n\n\n\nAn unauthenticated attacker who can reach an application that parses untrusted query strings or urlencoded bodies with both `comma: true` and `throwOnLimitExceeded: true` (both non-default) can bypass the configured limit with a single `a[]=` parameter and force the parser to allocate an array proportional to the request size. The cost is strictly linear in the attacker-supplied bytes (about 0.1 microseconds and 6 to 7 retained bytes per input byte; the same out-of-memory threshold as the documented default `throwOnLimitExceeded: false` path), so a transport-layer request or body size limit bounds it completely (and node's default maximum HTTP header size of 16 KB already bounds the request line, so multi-megabyte payloads need a body parser). The impact is that an opt-in hard limit fails open on one key spelling, not unbounded allocation from a small input.",
  "id": "CVE-2026-82562",
  "modified": "2026-09-02T03:30:30.578625264Z",
  "published": "2026-08-29T23:58:31.289Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://npmjs.com/qs"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82562.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-x5fp-wj9c-mxmx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82562"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ljharb/qs/commit/8859c37470e11b42b547b275e4e9bd0bc8cc5464"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ljharb/qs"
    }
  ],
  "related": [
    "GHSA-w7fw-mjwx-w883",
    "GHSA-x5fp-wj9c-mxmx"
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "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:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "qs.parse does not enforce arrayLimit on comma groups under bracket-push keys when throwOnLimitExceeded is set (incomplete fix for CVE-2026-2391)"
}