# CVE-2023-54397

## Summary

- **CVE ID:** CVE-2023-54397
- **Severity:** CRITICAL
- **CVSS Score:** 9 (CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:L/SI:H/SA:N)
- **CWE:** CWE-444
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 17, 2026

## Description

Tornado before 6.3.3 contains an HTTP request smuggling vulnerability due to improper parsing of Content-Length headers accepting non-standard characters. Attackers can send crafted HTTP requests with these characters to bypass proxy validation and smuggle requests when deployed behind certain proxies.

## Affected Products

- tornadoweb — tornado (0)
- tornadoweb — tornado (6.3.3)

## References

- [CNA](https://github.com/tornadoweb/tornado/security/advisories/GHSA-qppv-j76h-2rpx)
- [CNA](https://www.vulncheck.com/advisories/tornado-before-6.3.3-http-request-smuggling-via-content-length)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.37%
- **EPSS Percentile:** 30.4

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