CVE-2025-47287

Published May 15, 2025

Last updated a month ago

Python

Tornado

Overview

AI description

Automated description summarized from trusted sources.

CVE-2025-47287 affects the Tornado Python web framework and asynchronous networking library. The vulnerability stems from how Tornado's `multipart/form-data` parser handles errors. When the parser encounters malformed data, it logs a warning but continues parsing the remaining data instead of halting the process. This behavior allows remote attackers to generate a high volume of logs by sending crafted requests with malformed multipart form data. The excessive logging can overwhelm the logging subsystem, leading to a denial-of-service (DoS) attack because the logging subsystem operates synchronously. All Tornado versions prior to 6.5.0 are affected. A fix is available by upgrading to Tornado version 6.5.0. As a workaround, blocking `Content-Type: multipart/form-data` in a proxy can mitigate the risk.

Description: Tornado is a Python web framework and asynchronous networking library. When Tornado's ``multipart/form-data`` parser encounters certain errors, it logs a warning but continues trying to parse the remainder of the data. This allows remote attackers to generate an extremely high volume of logs, constituting a DoS attack. This DoS is compounded by the fact that the logging subsystem is synchronous. All versions of Tornado prior to 6.5.0 are affected. The vulnerable parser is enabled by default. Upgrade to Tornado version 6.50 to receive a patch. As a workaround, risk can be mitigated by blocking `Content-Type: multipart/form-data` in a proxy.
Source: security-advisories@github.com
NVD status: Awaiting Analysis

Risk scores

CVSS 3.1

Type: Secondary
Base score: 7.5
Impact score: 3.6
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity: HIGH

Weaknesses

security-advisories@github.com: CWE-770

Hype score: Not currently trending

References