CVE-2018-6789
Published: November 3, 2021
Official Description
Exim contains a buffer overflow vulnerability in the base64d function part of the SMTP listener that may allow for remote code execution.
CISA KEV Advisory
Exim Buffer Overflow Vulnerability
Exim contains a buffer overflow vulnerability in the base64d function part of the SMTP listener that may allow for remote code execution.
Apply updates per vendor instructions.
Risk Analysis
Exim contains a buffer overflow in its SMTP listener, which could allow a remote attacker to execute arbitrary code. With an EPSS score of 0.86439, there is a very high likelihood of this vulnerability being exploited, demanding prompt action.
This vulnerability is actively exploited in the wild and is part of CISA's KEV catalog, confirming its use by attackers. It is remotely exploitable.
Update your Exim mail server to a patched version. Ensure your mail server is properly secured and exposed only when necessary.
Technical Analysis
CVE-2018-6789 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2018-6789 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2018-6789 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1