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Vulnerabilities

Vulnerability · CVE-2023-54397

Tornado before 6.3.3 HTTP Request Smuggling via Content-Length

Published Sep 15, 2026 · catalog updated Sep 17, 2026 · Tornado before 6.3.3 HTTP

Check if you run it

No confirmed exploitation is on record for CVE-2023-54397. EPSS is 0.38%. Act only if a listed version of Tornado before 6.3.3 HTTP is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Tornado before 6.3.3 HTTP).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.38%
Remediation
Advisory link
Affected products
vendor tornadoweb tornado

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor tornadoweb tornadoversion unspecified

How to fix CVE-2023-54397

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2023-54397. EPSS is 0.38%. Act only if a listed version of Tornado before 6.3.3 HTTP is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-444: HTTP Request Smuggling. EPSS 0.38%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 17, 2026 · CVE.org

    Updated

    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.

  2. Oct 22, 2026 · Ubuntu Security Notices

    Detected

    CVE-2023-54397 is listed by USN-8952-1: Tornado vulnerabilities.

Sources

  • CVE.orgVulnerability recordCVE-2023-54397

    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

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-54397

    30-day exploitation probability 0.38%

    first.org
  • Ubuntu Security NoticesVendor advisoryCVE-2023-54397

    It was discovered that Tornado did not properly handle certain HTTP requests and network inputs. An attacker could possibly use these issues to cause a denial of service, expose sensitive information, or bypass access controls. (CVE-2023-54397, CVE-2024-14029, CVE-2026-91990, CVE

    ubuntu.com

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.