xine-lib is a multimedia library which can be utilized to create multimedia frontends. It includes functions to retrieve information about audio CD contents from public CDDB servers.
Ulf Harnhammar discovered a format string bug in the routines handling CDDB server response contents.
An attacker could submit malicious information about an audio CD to a public CDDB server (or impersonate a public CDDB server). When the victim plays this CD on a multimedia frontend relying on xine-lib, it could end up executing arbitrary code.
There is no known workaround at this time.
All xine-lib users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose media-libs/xine-lib