Vulnerability-Lookup

PYSEC-2026-140

Vulnerability from pysec - Published: 2026-03-11 20:16 - Updated: 2026-05-20 09:19

Details

Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.

Severity ?

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Impacted products

Name	purl
tornado	pkg:pypi/tornado

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "tornado",
        "purl": "pkg:pypi/tornado"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.5.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.2",
        "1.0",
        "1.1",
        "1.1.1",
        "1.2",
        "1.2.1",
        "2.0",
        "2.1",
        "2.1.1",
        "2.2",
        "2.2.1",
        "2.3",
        "2.4",
        "2.4.1",
        "3.0",
        "3.0.1",
        "3.0.2",
        "3.1",
        "3.1.1",
        "3.2",
        "3.2.1",
        "3.2.2",
        "4.0",
        "4.0.1",
        "4.0.2",
        "4.1",
        "4.1b2",
        "4.2",
        "4.2.1",
        "4.2b1",
        "4.3",
        "4.3b1",
        "4.3b2",
        "4.4",
        "4.4.1",
        "4.4.2",
        "4.4.3",
        "4.4b1",
        "4.5",
        "4.5.1",
        "4.5.2",
        "4.5.3",
        "4.5b1",
        "4.5b2",
        "5.0",
        "5.0.1",
        "5.0.2",
        "5.0a1",
        "5.0b1",
        "5.1",
        "5.1.1",
        "5.1b1",
        "6.0",
        "6.0.1",
        "6.0.2",
        "6.0.3",
        "6.0.4",
        "6.0a1",
        "6.0b1",
        "6.1",
        "6.1b1",
        "6.1b2",
        "6.2",
        "6.2b1",
        "6.2b2",
        "6.3",
        "6.3.1",
        "6.3.2",
        "6.3.3",
        "6.3b1",
        "6.4",
        "6.4.1",
        "6.4.2",
        "6.4b1",
        "6.5",
        "6.5.1",
        "6.5.2",
        "6.5.3",
        "6.5.4",
        "6.5b1"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31958",
    "GHSA-qjxf-f2mg-c6mc"
  ],
  "details": "Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.",
  "id": "PYSEC-2026-140",
  "modified": "2026-05-20T09:19:20.297525Z",
  "published": "2026-03-11T20:16:16.617Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-31958 (GCVE-0-2026-31958)

Vulnerability from cvelistv5 – Published: 2026-03-11 19:27 – Updated: 2026-04-01 14:32

Title

Tornado has a DoS due to too many multipart parts

Summary

Severity ?

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/tornadoweb/tornado/security/ad…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
tornadoweb	tornado	Affected: < 6.5.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-31958",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-12T19:55:43.911671Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-12T19:55:50.969Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2026-04-01T14:32:33.146Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "tornado",
          "vendor": "tornadoweb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.5.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-11T19:27:23.380Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc"
        }
      ],
      "source": {
        "advisory": "GHSA-qjxf-f2mg-c6mc",
        "discovery": "UNKNOWN"
      },
      "title": "Tornado has a DoS due to too many multipart parts"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-31958",
    "datePublished": "2026-03-11T19:27:23.380Z",
    "dateReserved": "2026-03-10T15:40:10.481Z",
    "dateUpdated": "2026-04-01T14:32:33.146Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-QJXF-F2MG-C6MC

Vulnerability from github – Published: 2026-03-12 14:19 – Updated: 2026-04-06 19:41

Summary

Tornado is vulnerable to DoS due to too many multipart parts

Details

In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts.

Tornado 6.5.5 introduces new limits on the size and complexity of multipart bodies, including a default limit of 100 parts per request. These limits are configurable if needed; see tornado.httputil.ParseMultipartConfig. It is also now possible to disable multipart/form-data parsing entirely if it is not required for the application.

Severity ?

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 6.5.4"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "tornado"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.5.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31958"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-12T14:19:52Z",
    "nvd_published_at": "2026-03-11T20:16:16Z",
    "severity": "HIGH"
  },
  "details": "In versions of Tornado prior to 6.5.5, the only limit on the number of parts in `multipart/form-data` is the `max_body_size` setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. \n\nTornado 6.5.5 introduces new limits on the size and complexity of multipart bodies, including a default limit of 100 parts per request. These limits are configurable if needed; see `tornado.httputil.ParseMultipartConfig`. It is also now possible to disable `multipart/form-data` parsing entirely if it is not required for the application.",
  "id": "GHSA-qjxf-f2mg-c6mc",
  "modified": "2026-04-06T19:41:28Z",
  "published": "2026-03-12T14:19:52Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31958"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tornadoweb/tornado/commit/119a195e290c43ad2d63a2cf012c29d43d6ed839"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/tornadoweb/tornado"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.5"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2026/04/msg00000.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Tornado is vulnerable to DoS due to too many multipart parts"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

PYSEC-2026-140

CVE-2026-31958 (GCVE-0-2026-31958)

GHSA-QJXF-F2MG-C6MC

Tags

Sightings

Nomenclature