The Xiph.org Free Lossless Audio Codec (FLAC) library is the reference implementation of the FLAC audio file format. It contains encoders and decoders in library and executable form.
Sean de Regge reported multiple integer overflows when processing FLAC media files that could lead to improper memory allocations resulting in heap-based buffer overflows.
A remote attacker could entice a user to open a specially crafted FLAC file or network stream with an application using FLAC. This might lead to the execution of arbitrary code with privileges of the user playing the file.
There is no known workaround at this time.
All FLAC users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=media-libs/flac-1.2.1-r1"
You should also run revdep-rebuild to rebuild any packages that depend on older versions of FLAC:
# revdep-rebuild --library=libFLAC.*