Pivotal Reactor Netty, versions prior to 0.8.11, passes headers through redirects, including authorization ones. A remote unauthenticated malicious user may gain access to credentials for a different server than they have access to.

The HttpClient from Reactor Netty, versions 0.9.x prior to 0.9.5, and versions 0.8.x prior to 0.8.16, may be used incorrectly, leading to a credentials leak during a redirect to a different domain. In order for this to happen, the HttpClient must have been explicitly configured to follow redirects.