CVE-2018-6789
CRITICALCISA KEVEPSS 100th pctlDescription
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.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
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.
Remediation due: 2022-05-03
Associated with ransomware campaigns
References
- http://openwall.com/lists/oss-security/2018/02/10/2
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html
- http://www.openwall.com/lists/oss-security/2018/02/07/2
- http://www.securityfocus.com/bid/103049
- http://www.securitytracker.com/id/1040461
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/
- https://exim.org/static/doc/security/CVE-2018-6789.txt
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1
- https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html
- https://usn.ubuntu.com/3565-1/
- https://www.debian.org/security/2018/dsa-4110
- https://www.exploit-db.com/exploits/44571/
- https://www.exploit-db.com/exploits/45671/
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-6789
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-07.