High severity · published Sep 15, 2026
CVE-2023-54397
Tornado before 6.3.3 HTTP Request Smuggling via Content-Length
7.5
CVSS
0.4%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
High
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
TO
tornado · tornadoweb
before 6.3.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-54397
CVE.org
https://www.cve.org/CVERecord?id=CVE-2023-54397
github.com
https://github.com/tornadoweb/tornado/security/advisories/GHSA-qppv-j76h-2rpx
www.vulncheck.com
https://www.vulncheck.com/advisories/tornado-before-6.3.3-http-request-smuggling-via-content-length
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