CVE-2020-28021 Command injection in n/a
Authenticated remote attackers can inject newlines into spool files via SMTP commands, leading to remote code execution as root.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-28021?
CVE-2020-28021 is a high-severity command injection vulnerability in Exim Exim, published on 6 May 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters. An authenticated remote SMTP client can insert newline characters into a spool file (which indirectly leads to remote code execution as root) via AUTH= in a MAIL FROM command.
Which versions are affected by CVE-2020-28021?
It affects 1 product.
Products include Exim Exim.
How do I fix CVE-2020-28021?
Upgrade to a fixed version.
Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.
Is CVE-2020-28021 being exploited?
There is no known exploitation of CVE-2020-28021 in the wild and no public exploit code.
Other vulnerabilities in Exim Exim
Sources
Also known as CLEANSTART-2025-GM62421, DEBIAN-CVE-2020-28021, GHSA-mrwv-vp3r-qhjm, UBUNTU-CVE-2020-28021.