Security Bulletin: CVE-2021-33037 Apache Tomcat 8.5.66 did not correctly parse the HTTP transfer-encoding request header leading to the possibility to request smuggling when used with a reverse proxy

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.

Vulnerability Details

CVEID:CVE-2021-33037
**DESCRIPTION:**Apache Tomcat is vulnerable to HTTP request smuggling, caused by improper parsing of the HTTP transfer-encoding request header. By sending a specially-crafted HTTP(S) transfer-encoding request header, an attacker could exploit this vulnerability to poison the web cache, bypass web application firewall protection, and conduct XSS attacks.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/205222 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)

Affected Products and Versions

Remediation/Fixes

Update to 7.2.0.2, 7.1.2.3, 7.0.5.7, 6.2.7.12 or later

Workarounds and Mitigations

None