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Fencer Vulns
high 7.5

CVE-2023-54397 json

Tornado before 6.3.3 HTTP Request Smuggling via Content-Length

published 2023-08-14 3 y ago modified 2026-09-17 52 d ago also EUVD-2023-60690 , GHSA-qppv-j76h-2rpx

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi tornado 6.3.3
  • tornadoweb tornado 6.3.3
  • python-tornado Debian 14, Debian 13 6.4.0-1

debian advisories DEBIAN-CVE-2023-54397

  • python-tornado Ubuntu Pro 16.04 LTS 4.2.1-1ubuntu3.1+esm4
  • python-tornado Ubuntu Pro 18.04 LTS 4.5.3-1ubuntu0.2+esm4
  • python-tornado Ubuntu Pro 22.04 LTS 6.1.0-3ubuntu0.1~esm6

ubuntu advisories UBUNTU-CVE-2023-54397

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-tornado SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 4.5.3-150000.3.31.1
  • python-tornado6 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 6.3.2-150400.9.27.1

suse advisories SUSE-SU-2026:4404-1SUSE-SU-2026:4403-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-54397 updated cvss 7.5

python-tornado: Tornado before 6.3.3 HTTP Request Smuggling via Content-Length

  • Red Hat Enterprise Linux 7 python-tornado
    affected: workaround, no fix available “Configure upstream reverse proxies or load balancers to strictly normalize or sanitize HTTP headers and reject malformed Content-Length headers before requests reach the Tornado application layer.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
52 d ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 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
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
CNA 4.0 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

Affected packages

ecosystem package affected fixed in
pypi tornado
<6.3.3
6.3.3

Affected products

  • tornadoweb tornado

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.