Fetchmail 5.0.8 through 6.3.21, when using NTLM authentication in debug mode, allows remote NTLM servers to (1) cause a denial of service (crash and delayed delivery of inbound mail) via a crafted NTLM response that triggers an out-of-bounds read in the base64 decoder, or (2) obtain sensitive information from memory via an NTLM Type 2 message with a crafted Target Name structure, which triggers an out-of-bounds read.

fetchmail 5.9.9 through 6.3.19 does not properly limit the wait time after issuing a (1) STARTTLS or (2) STLS request, which allows remote servers to cause a denial of service (application hang) by acknowledging the request but not sending additional packets.

fetchmail 4.6.3 through 6.3.16, when debug mode is enabled, does not properly handle invalid characters in a multi-character locale, which allows remote attackers to cause a denial of service (memory consumption and application crash) via a crafted (1) message header or (2) POP3 UIDL list.

socket.c in fetchmail before 6.3.11 does not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.