Festival is a Text to Speech Engine from The Centre for Speech Technology Research.
A vulnerability in Festival Server has an incorrect path in LD_LIBRARY_PATH, which allows local users to place a Trojan horse shared library in the current working directory.
A local attacker can execute arbitrary a Trojan horse shared library, potentially resulting in arbitrary code execution and privilege escalation.
There is no known workaround at this time.
All Festival users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-accessibility/festival-2.1"