CVE-2026-82397

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/tornadoweb/tornado/commit/8d6363ed7b69d5f0da806efe34d256627a2191de
https://github.com/tornadoweb/tornado/pull/3704
https://github.com/tornadoweb/tornado/releases/tag/v6.5.8
https://github.com/tornadoweb/tornado/security/advisories/GHSA-mpf4-983q-p7j4

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-31 22:17

Updated : 2026-09-09 21:09

NVD link : CVE-2026-82397

Mitre link : CVE-2026-82397

CVE.ORG link : CVE-2026-82397

JSON object : View

Products Affected

No product.

CWE

CWE-400

Uncontrolled Resource Consumption

CWE-1284

Improper Validation of Specified Quantity in Input

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