CVE-2023-54397

Tornado before 6.3.3 HTTP Request Smuggling via Content-Length

At a glance

Severity: CRITICAL 9.0
EPSS: EPSS 0.38 % · percentile 32 (2026-10-27)
State: PUBLISHED
Published: 2026-09-15
Updated: 2026-09-17
Assigner: VulnCheck
NVD status: Deferred

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.

Scores

Version	Score	Vector	Scored by
CVSS 4.0	CRITICAL 9.0	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	VulnCheck
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N	VulnCheck
CVSS 4.0	CRITICAL 9.0	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X	NVD · disclosure@vulncheck.com (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N	NVD · disclosure@vulncheck.com (Secondary)

Weaknesses (CWE)

CWE-444

Advisories

GHSA-qppv-j76h-2rpx — Tornado vulnerable to HTTP request smuggling via improper parsing of `Content-Length` fields and chunk lengths

European references

ENISA EUVD · EUVD-2023-60690
GCVE · GCVE-0-2023-54397

Affected products

Product	Versions
tornadoweb · tornado	affected 0 < 6.3.3 ; unaffected 6.3.3

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD