CVE-2026-31958

Aliases:GHSA-qjxf-f2mg-c6mcECHO-5939-f806-1836PYSEC-2026-140
Advisory lineage Upstream: 0 Downstream: 34
Modified
Published: 11 Mar 2026, 19:27
Last modified:01 Apr 2026, 14:32

Vulnerability Summary

Overall Risk (default)
medium
35/100
CVSS Score
8.7 HIGH
v4.0 (cve.org)
EPSS Score
0.38% LOW
0% probability +0.35%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

11 Mar 2026, 19:27
Published
Vulnerability first disclosed
01 Apr 2026, 14:32
Last Modified
Vulnerability information updated

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 Metrics

  • v4.0•HIGH•Score: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
  • v4.0•HIGH•Score: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
  • v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.38%• Percentile: 29%

Techniques & Countermeasures

  • CWE-400•Uncontrolled Resource Consumption

    The product does not properly control the allocation and maintenance of a limited resource.

Affected Systems

  • PyPI•tornado

    < 6.5.5

  • tornadoweb•tornado

    < 6.5.5

References (7)