Debian: DSA-4517-1 Critical: Exim4 Buffer Overflow Risk

"Zerons" and Qualys discovered that a buffer overflow triggerable in the
TLS negotiation code of the Exim mail transport agent could result in the
execution of arbitrary code with root privileges.

For the oldstable distribution (stretch), this problem has been fixed
in version 4.89-2+deb9u6.

For the stable distribution (buster), this problem has been fixed in
version 4.92-8+deb10u2.

We recommend that you upgrade your exim4 packages.

For the detailed security status of exim4 please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/exim4

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/