---
title: "CVE-2023-54397: Tornado - HTTP Request Smuggling"
description: "Tornado < 6.3.3 contains an HTTP request smuggling vulnerability caused by improper parsing of Content-Length headers accepting non-standard characters, letting attackers bypass proxy validation and smuggle requests, exploit requires deployment behind certain proxies."
url: https://panop.io/threat-heartbeat/CVE-2023-54397/
---

# CVE-2023-54397 Tornado - HTTP Request Smuggling

Tornado < 6.3.3 contains an HTTP request smuggling vulnerability caused by improper parsing of Content-Length headers accepting non-standard characters, letting attackers bypass proxy validation and smuggle requests, exploit requires deployment behind certain proxies.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.38% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2023-54397)

## Details

Type

HTTP Request Smuggling

Impact

HTTP Request Smuggling

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

Published

15 September 2026

Updated

15 October 2026

Weakness

[CWE-444](https://cwe.mitre.org/data/definitions/444.html)

## Vendor fix

Update to version 6.3.3 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2023-54397](https://nvd.nist.gov/vuln/detail/CVE-2023-54397)
- [https://www.vulncheck.com/advisories/tornado-before-6.3.3-http-request-smuggling-via-content-length](https://www.vulncheck.com/advisories/tornado-before-6.3.3-http-request-smuggling-via-content-length)
- [https://github.com/tornadoweb/tornado/security/advisories/GHSA-qppv-j76h-2rpx](https://github.com/tornadoweb/tornado/security/advisories/GHSA-qppv-j76h-2rpx)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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