CVE-2023-42115 Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability
Remote attackers can execute arbitrary code on Exim mail servers via an out-of-bounds write in the SMTP service without authentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-42115?
CVE-2023-42115 is a critical memory corruption vulnerability in Exim Exim, published on 3 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of a buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17434.
Weakness: CWE-787
Which versions are affected by CVE-2023-42115?
It affects 1 product.
Products include Exim Exim.
How do I fix CVE-2023-42115?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2023-42115 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-42115 exists.
Public exploit code: 2 proofs of concept on GitHub.
Other vulnerabilities in Exim Exim
Sources
Also known as CLEANSTART-2025-UQ49615, DEBIAN-CVE-2023-42115, GHSA-67rj-8f2h-26fc, UBUNTU-CVE-2023-42115.