An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.
openwall.com/lists/oss-security/2018/02/10/2
packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html
www.openwall.com/lists/oss-security/2018/02/07/2
www.securityfocus.com/bid/103049
www.securitytracker.com/id/1040461
devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/
exim.org/static/doc/security/CVE-2018-6789.txt
git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1
lists.debian.org/debian-lts-announce/2018/02/msg00009.html
usn.ubuntu.com/3565-1/
www.debian.org/security/2018/dsa-4110
www.exploit-db.com/exploits/44571/
www.exploit-db.com/exploits/45671/