CVE-2025-47287

NameCVE-2025-47287
DescriptionTornado 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4188-1, DSA-5938-1
Debian Bugs1105886

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python-tornado (PTS)bullseye6.1.0-1vulnerable
bullseye (security)6.1.0-1+deb11u2fixed
bookworm6.2.0-3+deb12u1vulnerable
bookworm (security)6.2.0-3+deb12u2fixed
sid, trixie6.4.2-3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python-tornadosourcebullseye6.1.0-1+deb11u2DLA-4188-1
python-tornadosourcebookworm6.2.0-3+deb12u2DSA-5938-1
python-tornadosource(unstable)6.4.2-21105886

Notes

https://github.com/tornadoweb/tornado/security/advisories/GHSA-7cx3-6m66-7c5m
https://github.com/tornadoweb/tornado/commit/b39b892bf78fe8fea01dd45199aa88307e7162f3

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