{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "6.5.9"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "75ef8b1cfa0e658aceb17c5a810ad1c74dc69bc7"
            },
            {
              "fixed": "03945136ea9746eccf61caf88edae39642e59c93"
            }
          ],
          "repo": "https://github.com/tornadoweb/tornado",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-3hv7-mjh2-fv65"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103261.json"
  },
  "details": "Tornado before 6.5.9 fails to limit the number of query string fields in HTTPServerRequest.__init__, allowing remote attackers to cause event-loop stalling by sending requests with thousands of query parameters. Attackers can send unauthenticated GET requests with unbounded query-string field counts to degrade response times for all clients sharing the same IOLoop.",
  "id": "CVE-2026-103261",
  "modified": "2026-10-03T03:30:15.808916203Z",
  "published": "2026-10-01T10:42:04.230Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103261.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-3hv7-mjh2-fv65"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-103261"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/tornado-before-6.5.9-denial-of-service-via-query-string"
    },
    {
      "type": "FIX",
      "url": "https://github.com/tornadoweb/tornado/commit/03945136ea9746eccf61caf88edae39642e59c93"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Tornado before 6.5.9 Denial of Service via Query String"
}