fkie_cve-2025-67726
Vulnerability from fkie_nvd
Published
2025-12-12 07:15
Modified
2025-12-12 15:17
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n²)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3.
References
security-advisories@github.comhttps://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd
security-advisories@github.comhttps://github.com/tornadoweb/tornado/releases/tag/v6.5.3
security-advisories@github.comhttps://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. If an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server\u0027s CPU usage increases quadratically (O(n\u00b2)) during parsing. Due to Tornado\u0027s single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period. This issue is fixed in version 6.5.3."
    }
  ],
  "id": "CVE-2025-67726",
  "lastModified": "2025-12-12T15:17:31.973",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2025-12-12T07:15:44.920",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.3"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-834"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}


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