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PYSEC-2026-140
Vulnerability from pysec - Published: 2026-03-11 20:16 - Updated: 2026-05-20 09:19
VLAI
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)
Impacted products
| Name | purl | tornado | pkg:pypi/tornado |
|---|
Aliases
{
"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"
}
]
}
BREW-JUPYTERLAB-CVE-2026-31958 (GHSA-QJXF-F2MG-C6MC)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-17 19:02 – Source website
VLAI
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
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.9",
"upstream_fixed_in": "6.5.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "jupyterlab",
"purl": "pkg:brew/jupyterlab"
},
"ranges": [
{
"events": [
{
"introduced": "1.2.0"
},
{
"fixed": "4.5.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.9",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.9"
}
]
},
"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": "BREW-jupyterlab-CVE-2026-31958",
"modified": "2026-09-17T19:02:18Z",
"published": "2026-08-13T17:01:18Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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": "1.7.3",
"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",
"upstream": [
"GHSA-qjxf-f2mg-c6mc",
"CVE-2026-31958",
"PYSEC-2026-140"
]
}
BREW-LIVERELOAD-CVE-2026-31958 (GHSA-QJXF-F2MG-C6MC)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:02 – Updated: 2026-09-17 19:41 – Source website
VLAI
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
References
| URL | Type | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "livereload",
"purl": "pkg:brew/livereload"
},
"ranges": [
{
"events": [
{
"introduced": "2.7.1"
},
{
"fixed": "2.7.1_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"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": "BREW-livereload-CVE-2026-31958",
"modified": "2026-09-17T19:41:55Z",
"published": "2026-08-13T17:02:57Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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": "1.7.3",
"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",
"upstream": [
"GHSA-qjxf-f2mg-c6mc",
"CVE-2026-31958",
"PYSEC-2026-140"
]
}
BREW-NVCHECKER-CVE-2026-31958 (GHSA-QJXF-F2MG-C6MC)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:19 – Updated: 2026-09-17 18:30 – Source website
VLAI
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
References
| URL | Type | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "nvchecker",
"purl": "pkg:brew/nvchecker"
},
"ranges": [
{
"events": [
{
"introduced": "2.7"
},
{
"fixed": "2.20_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"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": "BREW-nvchecker-CVE-2026-31958",
"modified": "2026-09-17T18:30:47Z",
"published": "2026-08-13T17:19:21Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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": "1.7.3",
"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",
"upstream": [
"GHSA-qjxf-f2mg-c6mc",
"CVE-2026-31958",
"PYSEC-2026-140"
]
}
BREW-SICKCHILL-CVE-2026-31958 (GHSA-QJXF-F2MG-C6MC)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:34 – Updated: 2026-09-17 18:24 – Source website
VLAI
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
References
| URL | Type | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "sickchill",
"purl": "pkg:brew/sickchill"
},
"ranges": [
{
"events": [
{
"introduced": "2023.5.30"
},
{
"fixed": "2024.3.1_5"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"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": "BREW-sickchill-CVE-2026-31958",
"modified": "2026-09-17T18:24:58Z",
"published": "2026-08-13T17:34:39Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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": "1.7.3",
"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",
"upstream": [
"GHSA-qjxf-f2mg-c6mc",
"CVE-2026-31958",
"PYSEC-2026-140"
]
}
BREW-SNAKEVIZ-CVE-2026-31958 (GHSA-QJXF-F2MG-C6MC)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:34 – Updated: 2026-09-17 19:58 – Source website
VLAI
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
References
| URL | Type | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "tornado",
"resource_purl": "pkg:pypi/tornado@6.5.8",
"upstream_fixed_in": "6.5.5"
},
"package": {
"ecosystem": "Homebrew",
"name": "snakeviz",
"purl": "pkg:brew/snakeviz"
},
"ranges": [
{
"events": [
{
"introduced": "2.2.0"
},
{
"fixed": "2.2.2_3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/tornado@6.5.8",
"name": "tornado",
"resource": "tornado",
"strategy": "registry",
"subject_version": "6.5.8"
}
]
},
"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": "BREW-snakeviz-CVE-2026-31958",
"modified": "2026-09-17T19:58:46Z",
"published": "2026-08-13T17:34:42Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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": "1.7.3",
"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",
"upstream": [
"GHSA-qjxf-f2mg-c6mc",
"CVE-2026-31958",
"PYSEC-2026-140"
]
}
CVE-2026-31958 (GCVE-0-2026-31958)
Vulnerability from cvelistv5 – Published: 2026-03-11 19:27 – Updated: 2026-04-01 14:32
VLAI
EPSS
VEX
Title
Tornado has a DoS due to too many multipart parts
Summary
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
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-12 19:55 UTC
CWE
- CWE-400 - Uncontrolled Resource Consumption
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/tornadoweb/tornado/security/ad… | x_refsource_CONFIRM |
| https://lists.debian.org/debian-lts-announce/2026… |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| tornadoweb | tornado |
Affected:
< 6.5.5
|
{
"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: 2026-06-08 19:51
VLAI
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
{
"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": "2026-06-08T19:51:12Z",
"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": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/tornado/PYSEC-2026-140.yaml"
},
{
"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"
}
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Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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