Another potential RCE in Exim! Let’s update, folks!
Jeremy Harris, from Exim Development Team, has discovered a heap-based buffer overflow issue in all versions of Exim servers up to and including 4.92.1.
The vulnerability (CVE-2019-16928) could allow remote attackers to cause a denial of service or execute arbitrary code on a targeted Exim mail server using a specially crafted line in the EHLO command with the rights of the targeted user: currently the public PoC exploit for this vulnerability allows only crash the Exim process by sending a long string in the EHLO command, though other commands could also be used to potentially execute arbitrary code.
Is there a patch?
Yep! Exim maintainers released an urgent security update after publishing the early warning, giving system administrators an early head-up on its upcoming security patches:
Fix === Download and build the fixed version 4.92.3 Tarballs: https://ftp.exim.org/pub/exim/exim4/ Git: https://github.com/Exim/exim.git - tag exim-4.92.3 - branch exim-4.92.3+fixes The tagged commit is the officially released version. The +fixes branch isn't officially maintained, but contains the security fix *and* useful fixes. If you can't install the above versions, ask your package maintainer for a version containing the backported fix. On request and depending on our resources we will support you in backporting the fix.