libtac in pamtacplus through 1.5.1 lacks a check for a failure of RANDbytes()/RANDpseudobytes(). This could lead to use of a non-random/predictable sessionid.
In pamtacplus.c in pamtacplus before 1.4.1, pamsmacctmgmt does not zero out the arep data structure.
In support.c in pamtacplus 1.3.8 through 1.5.1, the TACACS+ shared secret gets logged via syslog if the DEBUG loglevel and journald are used.