Sendmail 8.9.0 through 8.12.6 allows remote attackers to bypass relaying restrictions enforced by the 'check_relay' function by spoofing a blank DNS hostname.

Sendmail Consortium's Restricted Shell (SMRSH) in Sendmail 8.12.6, 8.11.6-15, and possibly other versions after 8.11 from 5/19/1998, allows attackers to bypass the intended restrictions of smrsh by inserting additional commands after (1) "||" sequences or (2) "/" characters, which are not properly filtered or verified.

Buffer overflow in Sendmail before 8.12.5, when configured to use a custom DNS map to query TXT records, allows remote attackers to cause a denial of service and possibly execute arbitrary code via a malicious DNS server.