Debian LTS DLA-2852-1: Apache Log4j2 DoS Threat Security Advisory

Improper validation of certificate with host mismatch in Apache Log4j SMTP
appender. This could allow an SMTPS connection to be intercepted by a
man-in-the-middle attack which could leak any log messages sent through
that appender.

CVE-2021-45105

Apache Log4j2 did not protect from uncontrolled recursion from
self-referential lookups. This allows an attacker with control over Thread
Context Map data to cause a denial of service when a crafted string is
interpreted.

For Debian 9 stretch, these problems have been fixed in version
2.12.3-0+deb9u1.

We recommend that you upgrade your apache-log4j2 packages.

For the detailed security status of apache-log4j2 please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/source-package/apache-log4j2

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