---
id: CVE-2023-54397
title: >-
  Tornado before 6.3.3 contains an HTTP request smuggling vulnerability due to
  improper parsing of Content-Length headers accepting non-standard characters
summary: >-
  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
  val…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N'
cwe:
  - CWE-444
vendor: tornadoweb
product: tornado
affected:
  - tornado < 6.3.3
patched:
  - tornado 6.3.3
published: '2026-09-15'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T15:16:39.103'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-54397'
references:
  - url: >-
      https://github.com/tornadoweb/tornado/security/advisories/GHSA-qppv-j76h-2rpx
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/tornado-before-6.3.3-http-request-smuggling-via-content-length
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/tornadoweb/tornado/commit/b7a5dd29bb02950303ae96055082c12a1ea0a4fe
  - url: 'https://github.com/tornadoweb/tornado'
tags:
  - nvd
  - cve.org
  - osv
  - pip
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-17T14:48:39.262559Z'
epss: 0.00367
epssPercentile: 0.30552
aliases:
  - GHSA-qppv-j76h-2rpx
ecosystem: pip
ingestedAt: '2026-09-15T15:39:12.928Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2023-54397)

Affected packages:

- `tornado < 6.3.3`

Patched in:

- `tornado 6.3.3`

Source: https://osv.dev/vulnerability/GHSA-qppv-j76h-2rpx