CVE-2023-54397: tornadoweb tornado HTTP Request/Response Smuggling
CVSS: 9.0v4.0CriticalDeferred
AliasesGHSA-qppv-j76h-2rpxUBUNTU-CVE-2023-54397DEBIAN-CVE-2023-54397
Published 15-09-2026Last modified 17-09-2026
Vulnerability summary
CVE-2023-54397 is a critical (CVSS 9.0) HTTP Request/Response Smuggling vulnerability in tornadoweb tornado. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 30.2% of scored vulnerabilities.
CVSS score
9.0/10
010
Critical · v4.0 (CVE.org)EPSS score
0.38%
0%100%
Low · +0.01 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 2 · Related 2Timeline
- 15-09-2026PublishedVulnerability first disclosed.
- 17-09-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
7 scores · 4 sources · 2 versionsCritical 9.0Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:L/SI:H/SA:NSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated9.0CriticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:L/SI:H/SA:N
- OSV · DebianEcosystem advisory · calculated9.0CriticalCVSS: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
- NVDNIST9.0CriticalCVSS: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
High 7.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:NSourcesAll 3 agree
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
EPSS trend
Probability
0.38%
Chance of exploitation in the next 30 days
Percentile
30%
Versus all other CVEs
30-day change
+0.01 pp
From 0.37% on 20-09-2026
20-09-202620-10-2026
EPSS score0.38%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian1 product
- python-tornadoAll versions (No fix recorded) | < 6.4.0-1
PyPI1 product
- tornado< 6.3.3
Tornadoweb1 product
- tornado< 6.3.3
Ubuntu1 product
- python-tornadoAll versions (No fix recorded)
4 vendors · 4 products
