CVE-2025-47287
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.
How to fix
- tornadoweb tornado6.5.0 or later
- tornado6.5 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| tornadoweb tornado | v < 6.5.0 | 6.5.0 |
| debian debian_linux | 11.0 | — |
| tornadoPyPI | v < 6.5 | 6.5 |
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