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Fencer Vulns
medium 5.3

CVE-2021-33037 json

Incorrect Transfer-Encoding handling with HTTP/1.0

published 2021-07-12 5 y ago modified 2026-10-08 31 d ago also BIT-tomcat-2021-33037 , EUVD-2021-1563 , GHSA-4vww-mc66-62m6

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
74.7%
EPSS 74.7% chance of exploitation in 30 days, percentile 99.5%
public exploits
0
none known

Summary

Apache Tomcat 10.0.0-M1 to 10.0.6, 9.0.0.M1 to 9.0.46 and 8.5.0 to 8.5.66 did not correctly parse the HTTP transfer-encoding request header in some circumstances leading to the possibility to request smuggling when used with a reverse proxy. Specifically: - Tomcat incorrectly ignored the transfer encoding header if the client declared it would only accept an HTTP/1.0 response; - Tomcat honoured the identify encoding; and - Tomcat did not ensure that, if present, the chunked encoding was the final encoding.

Patch / fix

  • maven org.apache.tomcat:tomcat 8.5.68, 9.0.48, 10.0.7
  • bitnami tomcat 8.5.67, 9.0.47, 10.0.7
  • oracle graph_server_and_client 21.4
  • mcafee epolicy_orchestrator 5.10.0
  • tomcat9 Debian 14, Debian 13, Debian 12 9.0.43-2

debian advisories DEBIAN-CVE-2021-33037

  • tomcat9 Ubuntu 18.04 LTS 9.0.16-3ubuntu0.18.04.2
  • tomcat9 Ubuntu 20.04 LTS 9.0.31-1ubuntu0.2

ubuntu advisories UBUNTU-CVE-2021-33037

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

  • jws5-tomcat jboss enterprise web server 5.6 9.0.50-3.redhat_00004.1.el7jws
  • jws5-tomcat jboss enterprise web server 5.6 9.0.50-3.redhat_00004.1.el8jws
  • jws5-tomcat-lib jboss enterprise web server 5.6 9.0.50-3.redhat_00004.1.el7jws
  • jws5-tomcat-lib jboss enterprise web server 5.6 9.0.50-3.redhat_00004.1.el8jws
  • jws5-tomcat-vault jboss enterprise web server 5.6 1.1.8-4.Final_redhat_00004.1.el7jws
  • jws5-tomcat-vault jboss enterprise web server 5.6 1.1.8-4.Final_redhat_00004.1.el8jws
  • jws5-tomcat-native jboss enterprise web server 5.6 1.2.30-3.redhat_3.el7jws
  • jws5-tomcat-native jboss enterprise web server 5.6 1.2.30-3.redhat_3.el8jws

red hat advisories RHSA-2021:4861

  • tomcat SLE Module for Web and Scripting 15 SP3, SLE Module for Web and Scripting 15 SP2 9.0.36-13.1
  • tomcat SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 9.0.36-3.84.1
  • tomcat SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +3 more 9.0.36-4.63.1
  • tomcat SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +3 more 9.0.36-3.71.1
  • javapackages-tools SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES 12 SP5 +3 more 2.0.1-13.1
  • tomcat SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 9.0.115-3.160.1

suse advisories SUSE-SU-2026:1058-1SUSE-SU-2021:3672-1SUSE-SU-2021:3670-1SUSE-SU-2021:3669-1SUSE-SU-2021:3602-1

  • tomcat openSUSE Tumbleweed 9.0.43-2.1
  • tomcat10 openSUSE Tumbleweed 10.1.14-1.1
  • tomcat openSUSE Leap 15.2 9.0.36-lp152.2.25.1
  • tomcat openSUSE Leap 15.3 9.0.36-13.1

opensuse advisories openSUSE-SU-2024:11618-1openSUSE-SU-2024:13441-1openSUSE-SU-2021:1490-1openSUSE-SU-2021:3672-1

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-2021-33037 updated cvss 4.3

tomcat: HTTP request smuggling when used with a reverse proxy

  • Red Hat OpenStack Platform 10 (Newton) opendaylight Red Hat OpenStack Platform 13 (Queens) opendaylight
    affected: no fix planned “Out of support scope”
  • Red Hat Fuse 7.11
    fixed: vendor fix RHSA-2022:5532
  • Red Hat JBoss Web Server 5
    fixed: vendor fix RHSA-2021:4863
  • Red Hat JBoss Web Server 5.6 for RHEL 7 Server jws5-tomcat 9.0.50-3.redhat_00004.1.el7jws, jws5-tomcat-native 1.2.30-3.redhat_3.el7jws, jws5-tomcat-lib 9.0.50-3.redhat_00004.1.el7jws, jws5-tomcat-javadoc 9.0.50-3.redhat_00004.1.el7jws, jws5-tomcat-selinux 9.0.50-3.redhat_00004.1.el7jws, jws5-tomcat-webapps 9.0.50-3.redhat_00004.1.el7jws, +9 more Red Hat JBoss Web Server 5.6 for RHEL 8 jws5-tomcat 9.0.50-3.redhat_00004.1.el8jws, jws5-tomcat-native 1.2.30-3.redhat_3.el8jws, jws5-tomcat-lib 9.0.50-3.redhat_00004.1.el8jws, jws5-tomcat-javadoc 9.0.50-3.redhat_00004.1.el8jws, jws5-tomcat-selinux 9.0.50-3.redhat_00004.1.el8jws, jws5-tomcat-webapps 9.0.50-3.redhat_00004.1.el8jws, +7 more
    fixed: vendor fix RHSA-2021:4861
  • Red Hat Support for Spring Boot 2.5.10
    fixed: vendor fix RHSA-2022:1179
  • Red Hat Decision Manager 7 tomcat Red Hat Enterprise Linux 6 tomcat6, tomcat6-lib, tomcat6-log4j, tomcat6-javadoc, tomcat6-webapps, tomcat6-el-2.1-api, +4 more Red Hat Enterprise Linux 7 tomcat, tomcat-lib, tomcat-jsvc, tomcat-javadoc, tomcat-webapps, tomcat-el-2.2-api, +4 more Red Hat Enterprise Linux 8 pki-servlet-engine, pki-servlet-4.0-api Red Hat JBoss Data Grid 6 jbossweb jbossweb Red Hat JBoss Data Virtualization 6 jbossweb jbossweb
    +4 more products
    Red Hat JBoss Enterprise Application Platform 6 jbossweb jbossweb Red Hat JBoss Fuse 6 tomcat Red Hat JBoss Web Server 3 tomcat Red Hat Process Automation 7 tomcat
    not affected: vulnerable code not present

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
yes
Technical impact
partial
Assessed
31 d ago

Exploit prediction

74.67% chance of exploitation in the next 30 days, higher than 99.5% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.apache.tomcat:tomcat
>=10.0.0-M1, <10.0.7
>=9.0.0-M1, <9.0.48
>=8.5.0, <8.5.68
10.0.7
9.0.48
8.5.68
bitnami tomcat
>=8.5.0, <8.5.67
>=9.0.0, <9.0.47
>=10.0.0, <10.0.7
8.5.67
9.0.47
10.0.7

Affected products

  • Apache Software Foundation Apache Tomcat

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.