LHa is a console-based program for packing and unpacking LHarc archives.
The command line argument as well as the archive parsing code of LHa lack sufficient bounds checking. Furthermore, a shell meta character command execution vulnerability exists in LHa, since it does no proper filtering on directory names.
Using a specially crafted command line argument or archive, an attacker can cause a buffer overflow and could possibly run arbitrary code. The shell meta character command execution could lead to the execution of arbitrary commands by an attacker using directories containing shell meta characters in their names.
There is no known workaround at this time.
All LHa users should upgrade to the latest stable version:
# emerge sync
# emerge -pv ">=app-arch/lha-114i-r4"
# emerge ">=app-arch/lha-114i-r4"