# CVE-2026-91990

## Summary

- **CVE ID:** CVE-2026-91990
- **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-770
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## Description

Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.

## Affected Products

- tornadoweb — tornado (0)
- tornadoweb — tornado (6.5.8)

## References

- [CNA](https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq)
- [CNA](https://www.vulncheck.com/advisories/tornado-before-6.5.8-memory-amplification-dos-via-multipart)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.41%
- **EPSS Percentile:** 35.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._