tornadoweb tornado up to 6.4.x Content-Type allocation of resources

Summaryinfo

A vulnerability identified as critical has been detected in tornadoweb tornado up to 6.4.x. The impacted element is an unknown function of the component Content-Type Handler. Performing a manipulation results in allocation of resources. This vulnerability is cataloged as CVE-2025-47287. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in tornadoweb tornado up to 6.4.x. It has been classified as critical. This affects some unknown functionality of the component Content-Type Handler. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2025-47287 since 05/05/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 237167 (SUSE SLED15 / SLES15 / openSUSE 15 Security Update : python-tornado6 (SUSE-SU-2025:01649-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.5.0 eliminates this vulnerability. Applying the patch b39b892bf78fe8fea01dd45199aa88307e7162f3 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (237167). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• tornadoweb

Name

• tornado

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4

License

• open-source

Website

• Product: https://github.com/tornadoweb/tornado/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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