# CVE-2026-31958

## Summary

- **CVE ID:** CVE-2026-31958
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-400
- **Published:** Mar 11, 2026
- **Last Modified:** Mar 12, 2026

## 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.

## Affected Products

- tornadoweb — tornado (< 6.5.5)

## References

- [CNA](https://github.com/tornadoweb/tornado/security/advisories/GHSA-qjxf-f2mg-c6mc)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.38%
- **EPSS Percentile:** 30.8

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._