CVE-2026-31958
Tornado is vulnerable to DoS due to too many multipart parts
7.5
HIGH
CVSS 3.1
EPSS 0.38%
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.
How to fix CVE-2026-31958
To remediate CVE-2026-31958, upgrade the affected package to a fixed version below.
- —upgrade to 6.1.0-1+deb11u4 or later
- —upgrade to 6.5.5 or later
- —upgrade to 6.5.5 or later
Is CVE-2026-31958 being exploited?
Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 6.1.0-1+deb11u4
- from 0, < 6.5.5
- from 0, < 6.5.5
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 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 |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |