ubuntu-cve-2026-82397
Vulnerability from osv_ubuntu
Published
2026-08-31 22:17
Modified
2026-09-02 16:28
Summary
Details
Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.
Severity
7.5 (High)
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-tornado",
"binary_version": "4.2.1-1ubuntu3.1+esm3"
},
{
"binary_name": "python3-tornado",
"binary_version": "4.2.1-1ubuntu3.1+esm3"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@4.2.1-1ubuntu3.1+esm3?arch=source\u0026distro=esm-infra/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.2.1-1ubuntu2",
"4.2.1-1ubuntu3",
"4.2.1-1ubuntu3.1",
"4.2.1-1ubuntu3.1+esm1",
"4.2.1-1ubuntu3.1+esm2",
"4.2.1-1ubuntu3.1+esm3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-tornado",
"binary_version": "4.5.3-1ubuntu0.2+esm3"
},
{
"binary_name": "python3-tornado",
"binary_version": "4.5.3-1ubuntu0.2+esm3"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:18.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@4.5.3-1ubuntu0.2+esm3?arch=source\u0026distro=esm-apps/bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.5.1-2.1~build2",
"4.5.2-1",
"4.5.3-1",
"4.5.3-1ubuntu0.1",
"4.5.3-1ubuntu0.2",
"4.5.3-1ubuntu0.2+esm1",
"4.5.3-1ubuntu0.2+esm2",
"4.5.3-1ubuntu0.2+esm3"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-tornado",
"binary_version": "6.0.3+really5.1.1-3ubuntu0.1~esm5"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@6.0.3+really5.1.1-3ubuntu0.1~esm5?arch=source\u0026distro=esm-apps/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"5.1.1-4ubuntu1",
"5.1.1-4ubuntu5",
"6.0.3+really5.1.1-2",
"6.0.3+really5.1.1-2build1",
"6.0.3+really5.1.1-2build2",
"6.0.3+really5.1.1-3",
"6.0.3+really5.1.1-3ubuntu0.1~esm1",
"6.0.3+really5.1.1-3ubuntu0.1~esm3",
"6.0.3+really5.1.1-3ubuntu0.1~esm5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-tornado",
"binary_version": "6.1.0-3ubuntu0.1~esm5"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:22.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@6.1.0-3ubuntu0.1~esm5?arch=source\u0026distro=esm-apps/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"6.1.0-1build1",
"6.1.0-2",
"6.1.0-3",
"6.1.0-3build1",
"6.1.0-3ubuntu0.1~esm1",
"6.1.0-3ubuntu0.1~esm2",
"6.1.0-3ubuntu0.1~esm4",
"6.1.0-3ubuntu0.1~esm5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-tornado",
"binary_version": "6.4.0-1ubuntu0.5"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@6.4.0-1ubuntu0.5?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"6.3.2-1",
"6.4.0-0ubuntu1",
"6.4.0-1",
"6.4.0-1build1",
"6.4.0-1ubuntu0.1",
"6.4.0-1ubuntu0.2",
"6.4.0-1ubuntu0.4",
"6.4.0-1ubuntu0.5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-tornado",
"binary_version": "6.5.4-0.1ubuntu0.1"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "python-tornado",
"purl": "pkg:deb/ubuntu/python-tornado@6.5.4-0.1ubuntu0.1?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"6.4.2-3",
"6.5.2-3",
"6.5.4-0.1",
"6.5.4-0.1ubuntu0.1"
]
}
],
"aliases": [],
"details": "Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.",
"id": "UBUNTU-CVE-2026-82397",
"modified": "2026-09-02T16:28:28Z",
"published": "2026-08-31T22:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-82397"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-82397"
},
{
"type": "REPORT",
"url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4"
},
{
"type": "REPORT",
"url": "https://github.com/tornadoweb/tornado/commit/8d6363ed7b69d5f0da806efe34d256627a2191de"
},
{
"type": "REPORT",
"url": "https://github.com/tornadoweb/tornado/pull/3704"
},
{
"type": "REPORT",
"url": "https://github.com/tornadoweb/tornado/releases/tag/v6.5.8"
}
],
"related": [],
"schema_version": "1.7.0",
"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": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-82397"
]
}
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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.
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.
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