Double Precision Courier e-mail MTA allows remote attackers to cause a denial of service (CPU consumption) via a message with an extremely large or negative value for the year, which causes a tight loop.

Courier sqwebmail before 0.40.0 does not quickly drop privileges after startup in certain cases, which could allow local users to read arbitrary files.

SQL injection vulnerability in the PostgreSQL auth module for courier 0.40 and earlier allows remote attackers to execute SQL code via the user name.

Multiple buffer overflows in (1) iso2022jp.c or (2) shiftjis.c for Courier-IMAP before 3.0.0, Courier before 0.45, and SqWebMail before 4.0.0 may allow remote attackers to execute arbitrary code "when Unicode character is out of BMP range."

spf.c in Courier Mail Server does not properly handle DNS failures when looking up Sender Policy Framework (SPF) records, which could allow attackers to cause memory corruption.

authpam.c in courier-authdaemon for Courier Mail Server 0.37.3 through 0.52.1, when using pam_tally, does not call the pam_acct_mgmt function to verify that access should be granted, which allows attackers to authenticate to the server using accounts that have been disabled.

libs/comverp.c in Courier MTA before 0.53.2 allows attackers to cause a denial of service (CPU consumption) via unknown vectors involving usernames that contain the "=" (equals) character, which is not properly handled during encoding.