Vulnerability · Published Sep 15, 2026 · Assigned by VulnCheck
CVE-2023-54397Tornado before 6.3.3 HTTP Request Smuggling via Content-Length
High 7.5
In plain English
A high-severity security flaw in tornado from tornadoweb. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 68.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-tornado | no fix listed | DEBIAN-CVE-2023-54397 |
| Debian:13 | python-tornado | 6.4.0-1 | DEBIAN-CVE-2023-54397 |
| Debian:14 | python-tornado | 6.4.0-1 | DEBIAN-CVE-2023-54397 |
| PyPI | tornado | 6.3.3 | GHSA-qppv-j76h-2rpx |
| Ubuntu:24.04:LTS | python-tornado | 6.4.0-1ubuntu0.6 | USN-8952-1 |
| Ubuntu:26.04:LTS | python-tornado | 6.5.4-0.1ubuntu0.2 | USN-8952-1 |
| Ubuntu:26.10 | python-tornado | 6.5.5-5ubuntu1.1 | USN-8952-1 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| tornadoweb | tornado | 0 – before 6.3.3 |
Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
References
- GitHub Security Advisory (GHSA-qppv-j76h-2rpx) vendor-advisory
- VulnCheck Advisory: Tornado before 6.3.3 HTTP Request Smuggling via Content-Length third-party-advisory