UpHeron
All vulnerabilities

Servers and applications

CVE-2018-6789

An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.

Actively exploited: CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021.

Severity
Critical 9.8
Published
8 Feb 2018
Last changed
17 Jun 2026
Added to UpHeron
1 Nov 2026
Fixed in
4.90.1
Exploit chance
82% in the next 30 daysHigher than 99% of CVEs. EPSS by FIRST, 11 Nov 2026
Weakness
Buffer overflow (CWE-120)
Attack
Over the network · No login needed · No user action needed
Attacker can
Read data · Change data · Take it down
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Sources
NVD

Affected software

SoftwareAffected versions
EximServers and applications · cpe:a:exim:exim
  • Every version before 4.90.1

Known exploited

CISA name
Exim Buffer Overflow Vulnerability
Required action
Apply updates per vendor instructions.
Due for US agencies
3 May 2022
Used in ransomware
Yes, known

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2018-6789
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2018-6789