CVE-2018-6789

critical

Description

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.

From the Tenable Blog

Exim Buffer Overflow RCE Vulnerability (CVE-2018-6789) – What You Need to Know

Exim Buffer Overflow RCE Vulnerability (CVE-2018-6789) – What You Need to Know

Published: 2018-03-07

On February 10, the Unix-based email server Exim released an update to address a heap buffer overflow vulnerability that can be used by an unauthenticated attacker to remotely execute arbitrary code. The flaw, assigned CVE-2018-6789, is noted to exist in all versions of Exim, prior to their latest release, 4.90.1, which means the attack surface potential is very wide.

References

https://www.debian.org/security/2018/dsa-4110

https://usn.ubuntu.com/3565-1/

https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html

http://www.openwall.com/lists/oss-security/2018/02/07/2

http://openwall.com/lists/oss-security/2018/02/10/2

https://media.defense.gov/2020/Oct/20/2002519884/-1/-1/0/CSA_CHINESE_EXPLOIT_VULNERABILITIES_UOO179811.PDF

https://www.exploit-db.com/exploits/45671/

https://www.exploit-db.com/exploits/44571/

https://www.tenable.com/blog/government-agencies-warn-of-state-sponsored-actors-exploiting-publicly-known-vulnerabilities

https://www.tenable.com/blog/how-covid-19-response-is-expanding-the-cyberattack-surface

https://www.tenable.com/blog/cve-2019-15846-unauthenticated-remote-command-execution-flaw-disclosed-for-exim

https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1

https://exim.org/static/doc/security/CVE-2018-6789.txt

https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/

http://www.securitytracker.com/id/1040461

http://www.securityfocus.com/bid/103049

http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html

Details

Source: Mitre, NVD

Published: 2018-02-08

Updated: 2025-03-14

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

Severity: High

CVSS v3

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: Critical

EPSS

EPSS: 0.72078