The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.
Created exim tracking bugs for this issue:
Affects: epel-all [bug 1517686]
Affects: fedora-all [bug 1517687]