libass: Denial of service

Background

libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format.

Description

A one-byte buffer overwrite in ASS font decoding could trigger an assertion failure resulting in denial of service.

Impact

An attacker with control over the ASS track input to libass via an application using it could trigger a denial of service.

Workaround

There is no known workaround at this time.

Resolution

All libass users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=media-libs/libass-0.15.1"