In Puma (RubyGem) before 4.3.5 and 3.12.6, a client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client. If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client. This is a similar but different vulnerability from CVE-2020-11076. The problem has been fixed in Puma 3.12.6 and Puma 4.3.5.

Citrix Gateway 11.1, 12.0, and 12.1 has an Inconsistent Interpretation of HTTP Requests. NOTE: Citrix disputes the reported behavior as not a security issue. Citrix ADC only caches HTTP/1.1 traffic for performance optimization

Vulnerability in the Oracle Production Scheduling product of Oracle E-Business Suite (component: Import Utility). Supported versions that are affected are 12.2.4-12.2.12. Easily exploitable vulnerability allows unauthenticated attacker with network access via HTTP to compromise Oracle Production Scheduling. Successful attacks of this vulnerability can result in unauthorized creation, deletion or modification access to critical data or all Oracle Production Scheduling accessible data. CVSS 3.1 Base Score 7.5 (Integrity impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).

goliath through 1.0.6 allows request smuggling attacks where goliath is used as a backend and a frontend proxy also being vulnerable. It is possible to conduct HTTP request smuggling attacks by sending the Content-Length header twice. Furthermore, invalid Transfer Encoding headers were found to be parsed as valid which could be leveraged for TE:CL smuggling attacks.

reel through 0.6.1 allows Request Smuggling attacks due to incorrect Content-Length and Transfer encoding header parsing. It is possible to conduct HTTP request smuggling attacks by sending the Content-Length header twice. Furthermore, invalid Transfer Encoding headers were found to be parsed as valid which could be leveraged for TE:CL smuggling attacks. Note: This project is deprecated, and is not maintained any more.

Netty 4.1.43.Final allows HTTP Request Smuggling because it mishandles Transfer-Encoding whitespace (such as a [space]Transfer-Encoding:chunked line) and a later Content-Length header. This issue exists because of an incomplete fix for CVE-2019-16869.

In Ktor before 1.3.0, request smuggling is possible when running behind a proxy that doesn't handle Content-Length and Transfer-Encoding properly or doesn't handle \n as a headers separator.