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CVE-2026-31958

Tornado has a DoS due to too many multipart parts

Published: Mar 11, 2026Updated: Apr 1, 2026 Sources: CVE List NVD GHSA BDUCWE-400
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.4%
Top 70.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Tornado is a Python web framework and asynchronous networking library. In versions of Tornado prior to 6.5.5, the only limit on the number of parts in multipart/form-data is the max_body_size setting (default 100MB). Since parsing occurs synchronously on the main thread, this creates the possibility of denial-of-service due to the cost of parsing very large multipart bodies with many parts. This vulnerability is fixed in 6.5.5.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-400

Affected Products

tornadotornadoweb
Library
OSS Libraries / web-framework
tornadoPyPIOSS Libraries
Red Hat Enterprise LinuxRed Hat Inc.
On-premOS
Operating Systems / linux-distro
UbuntuCanonical Ltd.
On-premOS
Operating Systems / linux-distro
Debian GNU/LinuxСообщество свободного программного обеспечения
On-premOS
Operating Systems / linux-distro
tornadoweboss-projectOSS Librariesaka tornado
pypipackage-ecosystemOSS Libraries
red hat inc.commercialUSOperating Systemsaka red hat
canonical ltd.commercialGBOperating Systemsaka canonical
сообщество свободного программного обеспеченияoss-projectOperating Systemsaka сообщество свободного программного обеспечения, fsf
and 8 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc
github.com
https://nvd.nist.gov/vuln/detail/CVE-2026-31958
nvd.nist.gov
https://github.com/tornadoweb/tornado/commit/119a195e290c43ad2d63a2cf012c29d43d6ed839
github.com
and 13 more references View all →

Timeline

Published
Mar 11, 2026
Last Updated
Apr 1, 2026

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