Exim Buffer Overflow Vulnerability

CRITICAL 9.8EXPLOITED (CISA KEV)CVE-2018-6789 · Published 08/02/2018 · updated 17/06/2026

Exim Buffer Overflow Vulnerability. Actively exploited: CISA added this vulnerability to its Known Exploited Vulnerabilities catalog on 03/11/2021. Patch affected systems as an emergency. It is known to be used in ransomware campaigns.

Package	Affected versions	Patched versions
exim exim	`< 4.90.1`	`4.90.1`

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.

References

openwall.com/lists/oss-security/2018/02/10/2 · Mailing List
packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html · Exploit
openwall.com/lists/oss-security/2018/02/07/2 · Mailing List
securityfocus.com/bid/103049 · Broken Link
securitytracker.com/id/1040461 · Broken Link
devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en · Exploit
exim.org/static/doc/security/CVE-2018-6789.txt · Vendor Advisory
git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1 · Patch
lists.debian.org/debian-lts-announce/2018/02/msg00009.html · Mailing List
usn.ubuntu.com/3565-1 · Third Party Advisory
debian.org/security/2018/dsa-4110 · Mailing List
exploit-db.com/exploits/44571 · Exploit
exploit-db.com/exploits/45671 · Exploit
cisa.gov/known-exploited-vulnerabilities-catalog · US Government Resource
CISA KEV · CVE-2018-6789

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