A tnef security update has been released for Debian GNU/Linux 9 LTS to address an issue where emails with a crafted winmail.dat application/ms-tnef attachment might allow an attacker to change .ssh/authorized_keys.

DLA 2748-1: tnef security update

- -------------------------------------------------------------------------
Debian LTS Advisory DLA-2748-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Thorsten Alteholz
August 23, 2021   https://wiki.debian.org/LTS
- -------------------------------------------------------------------------

Package : tnef
Version : 1.4.12-1.2+deb9u1
CVE ID : CVE-2019-18849

An issue has been found in tnef, a tool to unpack MIME application/ms-tnef
attachments.
Using emails with a crafted winmail.dat application/ms-tnef attachment
might allow an attacker to change .ssh/authorized_keys.

For Debian 9 stretch, this problem has been fixed in version
1.4.12-1.2+deb9u1.

We recommend that you upgrade your tnef packages.

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

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