Ulf Härnhammar discovered two stack buffer overflows and two directory
traversal flaws in LHA.  An attacker could exploit the buffer
overflows by creating a carefully crafted LHA archive in such a way
that arbitrary code would be executed when the archive is tested or
extracted by a victim.  CAN-2004-0234.  An attacker could exploit the
directory traversal issues to create files as the victim outside of
the expected directory.  CAN-2004-0235.

These issues seem to be fixed in FC2t3. You can probably just rebuild
lha-1.14i-14 from FC2 for FC1.