It indicates a possible attempt of a Directory Traversal attack against Icecast. Icecast is an Open Source Audio Streaming server for both Microsoft Windows and Unix. It is vulnerable to a Directory Traversal attack because it does not sufficiently filter user supplied URLs.
Icecast 1.0.0 ? 1.3.9-2.
Upgrade to Icecast Icecast 1.3.10 -1 or later versions.