Headline
GHSA-7cx3-6m66-7c5m: Tornado vulnerable to excessive logging caused by malformed multipart form data
Summary
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 6.5.0 are affected. The vulnerable parser is enabled by default.
Solution
Upgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking Content-Type: multipart/form-data in a proxy.
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- GitHub Advisory Database
- GitHub Reviewed
- CVE-2025-47287
Tornado vulnerable to excessive logging caused by malformed multipart form data
High severity GitHub Reviewed Published May 15, 2025 in tornadoweb/tornado • Updated May 16, 2025
Package
pip tornado (pip)
Affected versions
< 6.5.0
Description
Summary
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 6.5.0 are affected. The vulnerable parser is enabled by default.
Solution
Upgrade to Tornado version 6.5. In the meantime, risk can be mitigated by blocking Content-Type: multipart/form-data in a proxy.
References
- GHSA-7cx3-6m66-7c5m
- https://nvd.nist.gov/vuln/detail/CVE-2025-47287
- tornadoweb/tornado@b39b892
Published to the GitHub Advisory Database
May 16, 2025
Last updated
May 16, 2025
EPSS score