Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Improper Input Validation vulnerability in Apache Tomcat. Tomcat versions 8.5.0 through 8.5.95, 9.0.0-M1 through 9.0.82, 10.1.0-M1 through 10.1.15, and 11.0.0-M1 through 11.0.0-M10 did not correctly parse HTTP trailer headers. A trailer header that exceeded the header size limit could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy. Users are recommended to upgrade, which fix the issue.
CWE-444 - HTTP Request Smuggling
Entities such as web servers, web caching proxies, and application firewalls could parse HTTP requests differently. When there are two or more such entities in the path of an HTTP request, an attacker can send a specially crafted HTTP request that is seen as two different sets of requests by the attacked devices, allowing the attacker to smuggle a request into one device without the other device being aware of it. Such a vulnerability can prove devastating, for it enables further attacks on the application, like web cache poisoning, session hijacking, cross-site scripting, security bypassing, and sensitive information exposure.