CVE-2018-6789VulnerabilityPublished 11/03/2021Updated 10/24/2026

CVE-2018-6789: Exim Buffer Overflow Vulnerability

Affects Exim EximSource CISA KEV

Severity

High

No CVSS score published yet

Exploitation: Actively exploited – in CISA KEV since 11/03/2021
KEV deadline: 05/03/2022
Ransomware: Used in ransomware campaigns
EPSS: 82.1% chance of exploitation in 30 days – higher than 99% of CVEs

What to do

CISA required action

Apply updates per vendor instructions.

nvd.nist.gov/vuln/detail/CVE-2018-6789 (opens in a new tab)

Description

CVE-2018-6789 is a high-severity buffer overflow vulnerability in the Exim mail transfer agent's base64d function within the SMTP listener. This flaw may allow remote code execution. It has been exploited in the wild and is known to have been used in ransomware campaigns. No specific affected versions or patch information is provided in the available data.

Summary

Exim contains a buffer overflow vulnerability in the base64d function of its SMTP listener component. This vulnerability can be exploited remotely to execute arbitrary code on the affected system. The issue is tracked as CVE-2018-6789 and is associated with CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). Exploitation has been observed in the wild, including use in ransomware campaigns. No explicit patch or remediation details are provided in the input data.

Impact

Successful exploitation of this vulnerability may result in remote code execution, potentially allowing attackers to take control of the affected system. The vulnerability has been exploited in the wild and leveraged in ransomware campaigns, indicating active threat and significant risk to affected systems.

Mitigation

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is confirmed, organizations should monitor vendor communications and apply any available updates promptly. No vendor advisory or patch links were provided in the input data.

Weaknesses

CWE-119Buffer Errors (Memory Bounds) (opens in a new tab)

What to do

Description

AnalysisAI-generated, updated 10/24/2026, 09:26:49 UTC

Weaknesses

References

Related threats