Exim < 4.43 - Buffer Overflow via IPv6 Address or DNS PTR Lookup
Multiple buffer overflows in Exim before 4.43 may allow attackers to execute arbitrary code via (1) an IPv6 address with more than 8 components, as demonstrated using the -be command line option, which triggers an overflow in the host_aton function, or (2) the -bh command line option or dnsdb PTR lookup, which triggers an overflow in the dns_build_reverse function.