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 hostaton function, or (2) the -bh command line option or dnsdb PTR lookup, which triggers an overflow in the dnsbuildreverse function.

Buffer overflow in the spabase64tobits function in Exim before 4.43, as originally obtained from Samba code, and as called by the authspaclient function, may allow attackers to execute arbitrary code during SPA authentication.