A flaw was found in the loadbuf function in formisc.c. When the buffer is too small, the function tries to resize it, but only by Bsize (=128) bytes. This is not necessarily enough and could cause denial of service.

References:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=876511

Race condition in signal handling of procmail 3.20 and earlier, when running setuid, allows local users to cause a denial of service or gain root privileges by sending a signal while a signal handling routine is already running.

A race condition in how procmail handles .procmailrc files allows a local user to read arbitrary files available to the user who is running procmail.

Buffer overflow in procmail before version 3.12 allows remote or local attackers to execute commands via expansions in the procmailrc configuration file.