Requests forwarded by ReverseProxy include the raw query parameters from the inbound request, including unparsable parameters rejected by net/http. This could permit query parameter smuggling when a Go proxy forwards a parameter with an unparsable value. After fix, ReverseProxy sanitizes the query parameters in the forwarded query when the outbound request's Form field is set after the ReverseProxy. Director function returns, indicating that the proxy has parsed the query parameters. Proxies which do not parse query parameters continue to forward the original query parameters unchanged.

In Puma (RubyGem) before 4.3.4 and 3.12.5, an attacker could smuggle an HTTP response, by using an invalid transfer-encoding header. The problem has been fixed in Puma 3.12.5 and Puma 4.3.4.

Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') vulnerability in mod_proxy_ajp of Apache HTTP Server allows an attacker to smuggle requests to the AJP server it forwards requests to. This issue affects Apache HTTP Server Apache HTTP Server 2.4 version 2.4.53 and prior versions.

Improper Input Validation vulnerability in HTTP/2 request validation of Apache Traffic Server allows an attacker to create smuggle or cache poison attacks. This issue affects Apache Traffic Server 8.0.0 to 9.1.2.

Waitress is a Web Server Gateway Interface server for Python 2 and 3. When using Waitress versions 2.1.0 and prior behind a proxy that does not properly validate the incoming HTTP request matches the RFC7230 standard, Waitress and the frontend proxy may disagree on where one request starts and where it ends. This would allow requests to be smuggled via the front-end proxy to waitress and later behavior. There are two classes of vulnerability that may lead to request smuggling that are addressed by this advisory: The use of Python's `int()` to parse strings into integers, leading to `+10` to be parsed as `10`, or `0x01` to be parsed as `1`, where as the standard specifies that the string should contain only digits or hex digits; and Waitress does not support chunk extensions, however it was discarding them without validating that they did not contain illegal characters. This vulnerability has been patched in Waitress 2.1.1. A workaround is available. When deploying a proxy in front of waitress, turning on any and all functionality to make sure that the request matches the RFC7230 standard. Certain proxy servers may not have this functionality though and users are encouraged to upgrade to the latest version of waitress instead.

Puma is a simple, fast, multi-threaded, parallel HTTP 1.1 server for Ruby/Rack applications. When using Puma behind a proxy that does not properly validate that the incoming HTTP request matches the RFC7230 standard, Puma and the frontend proxy may disagree on where a request starts and ends. This would allow requests to be smuggled via the front-end proxy to Puma. The vulnerability has been fixed in 5.6.4 and 4.3.12. Users are advised to upgrade as soon as possible. Workaround: when deploying a proxy in front of Puma, turning on any and all functionality to make sure that the request matches the RFC7230 standard.

An issue was discovered in Ruby through 2.5.8, 2.6.x through 2.6.6, and 2.7.x through 2.7.1. WEBrick, a simple HTTP server bundled with Ruby, had not checked the transfer-encoding header value rigorously. An attacker may potentially exploit this issue to bypass a reverse proxy (which also has a poor header check), which may lead to an HTTP Request Smuggling attack.

ATS negative cache option is vulnerable to a cache poisoning attack. If you have this option enabled, please upgrade or disable this feature. Apache Traffic Server versions 7.0.0 to 7.1.11 and 8.0.0 to 8.1.0 are affected.

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.