CVE-2021-33037

Description

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.

How to fix CVE-2021-33037

To remediate CVE-2021-33037, upgrade the affected package to a fixed version below.

• —upgrade to 8.5.67 or later
• —upgrade to 9.0.43-2~deb11u1 or later
• —upgrade to 10.0.7 or later

Is CVE-2021-33037 being exploited?

Low — EPSS is 1.9%, meaning exploitation activity has not been observed at scale.

Affected packages (3)

• >= 8.5.0, < 8.5.67, >= 9.0.0, < 9.0.47, >= 10.0.0, < 10.0.7
• from 0, < 9.0.43-2~deb11u1
• >= 10.0.0-M1, < 10.0.7

CVSS scores

References (39)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-33037
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-33037
• PATCHgithub.com/apache/tomcat
• WEBgithub.com/apache/tomcat/commit/05f9e8b00f5d9251fcd3c95dcfd6cf84177f46c8