Vulnerability record · CVE-2025-47287 · published 15 May 2025
CVE-2025-47287: Tornadoweb tornado allocation without limits vulnerability
Tornadoweb · Tornado
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.
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
| Link | Tags |
|---|---|
| https://github.com/tornadoweb/tornado/commit/b39b892bf78fe8fea01dd45199aa88307e7162f3 | Patch |
| https://github.com/tornadoweb/tornado/security/advisories/GHSA-7cx3-6m66-7c5m | Vendor Advisory |
| https://lists.debian.org/debian-lts-announce/2025/05/msg00038.html | Mailing ListThird Party Advisory |
Track CVE-2025-47287 inside VULONE
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Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2025-47287), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.
