CVE-2019-16928 Exim Out-of-bounds Write

What is CVE-2019-16928?

CVE-2019-16928 is a critical memory corruption vulnerability in Canonical Ubuntu Linux, published on 27 Sep 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than CVE-2019-15846. There is a heap-based buffer overflow in string_vformat in string.c involving a long EHLO command.

Weakness: CWE-787

Which versions are affected by CVE-2019-16928?

It affects 4 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Exim Exim, Fedoraproject Fedora.

How do I fix CVE-2019-16928?

Apply the vendor's patch. US federal agencies must fix it by 17 Mar 2022.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2019-16928 being exploited?

Yes. Attackers have exploited CVE-2019-16928 in the wild since at least 3 Mar 2022.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8
• CVE-2013-0422 Oracle JRE Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CLEANSTART-2025-PV46598, DEBIAN-CVE-2019-16928, DSA-4536-1, GHSA-xg2f-gj2p-r7xq.