Python Library Tornado < 6.5.8 DoS (CVE-2026-82397)

high Nessus Plugin ID 344487

Synopsis

A Python library installed on the remote host is affected by a denial of service vulnerability.

Description

The version of the Tornado Python package installed on the remote host is prior to 6.5.8. It is, therefore, affected by a denial of service vulnerability:

- 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. (CVE-2026-82397)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Tornado version 6.5.8 or later.

Plugin Details

Severity: High

ID: 344487

File Name: python_tornado_6_5_8.nasl

Version: 1.1

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 9/10/2026

Updated: 9/10/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.64

CVSS v2

Risk Factor: High

Base Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2026-82397

CVSS v3

Risk Factor: High

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/a:tornadoweb:tornado

Patch Publication Date: 8/6/2026

Vulnerability Publication Date: 8/31/2026

Reference Information

CVE: CVE-2026-82397

Detections

Analytics