Async Http Client (aka async-http-client) before 2.0.35 can be tricked into connecting to a host different from the one extracted by java.net.URI if a '?' character occurs in a fragment identifier. Similar bugs were previously identified in cURL (CVE-2016-8624) and Oracle Java 8 java.net.URL.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.