Versions mentioned in the description apply to the upstream
Remediation section below for
Debian:9 relevant versions.
Exim 4 before 4.94.2 has Improper Restriction of Write Operations within the Bounds of a Memory Buffer. This occurs when processing name=value pairs within MAIL FROM and RCPT TO commands.
exim4 to version 4.89-2+deb9u8 or higher.