CVE
CVE-2026-31958
Tornado has a DoS due to too many multipart parts
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 maxbodysize 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.
Package Versions Affected
Package Version
patch Availability
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CVSS Version
Severity
Base Score
CVSS Version
Score Vector
C
H
U
8.7
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4.0
CVSS: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
C
H
U
0
-
C
H
U
-
Related Resources
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References
https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31958.json, https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc, https://nvd.nist.gov/vuln/detail/CVE-2026-31958
Basic Information
Ecosystem
