CVE-2025-47287

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.

Affected versions

All versions of Tornado prior to 6.5 are affected. The vulnerable parser is enabled by default.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2025-47287 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (6.5); upgrading removes the vulnerable code path.

Kodem intelligence

Upgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking Content-Type: multipart/form-data in a proxy.

1. What is CVE-2025-47287? CVE-2025-47287 is a high-severity allocation of resources without limits or throttling vulnerability in tornado (pip), affecting versions < 6.5. It is fixed in 6.5. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2025-47287? CVE-2025-47287 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of tornado are affected by CVE-2025-47287? tornado (pip) versions < 6.5 is affected.
4. Is there a fix for CVE-2025-47287? Yes. CVE-2025-47287 is fixed in 6.5. Upgrade to this version or later.
5. Is CVE-2025-47287 exploitable, and should I be worried? Whether CVE-2025-47287 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-47287 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-47287? Upgrade tornado to 6.5 or later.