Vulnerability record

CVE-2019-10149

Exim Mail Transfer Agent (MTA) Improper Input Validation

CriticalExploitation confirmedCISA KEV

What should I do?

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Mail Transfer Agent (MTA), fix it now.

CISA required action: Apply updates per vendor instructions.

US federal civilian agencies must remediate by Jul 10, 2022.

Patch status

Official fix available since Sep 30, 2026

Apply the vendor's update to every affected system. Check the fixed-in versions below where known.

Basis: NVD patch reference

Patch or advisory on openwall.com (opens in a new tab)

Description

A flaw was found in Exim versions 4.87 to 4.91 (inclusive). Improper validation of recipient address in deliver_message() function in /src/deliver.c may lead to remote command execution.

Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.

Affected products

Products affected by this vulnerability, with versions and the source of each entry
Product	Vendor	Affected versions	Source
Exim	Exim	>= 4.87, <= 4.91	NVD
Mail Transfer Agent (MTA)	Exim	—	KEV

Sources: NVD = NIST National Vulnerability Database; KEV = CISA Known Exploited Vulnerabilities catalog.

Intelligence timeline

Developments from the last 30 days, newest first.

CVSS scoredUpdateKEVSep 30, 2026
CVE-2019-10149 scored CVSS 9.8: Exim Mail Transfer Agent (MTA), Exim Mail Transfer Agent (MTA) Improper Input Validation
CISA lists this as exploited in the wild. Unpatched Mail Transfer Agent (MTA) systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch releasedUpdateKEVSep 30, 2026
Patch released for CVE-2019-10149: Exim Mail Transfer Agent (MTA), Exim Mail Transfer Agent (MTA) Improper Input Validation
An official fix is now available for Exim Mail Transfer Agent (MTA). This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference

1 earlier event is available with a subscription. See plans.

Coverage

We have not published a story about this vulnerability yet.

References

nvd.nist.gov https://nvd.nist.gov/vuln/detail/CVE-2019-10149
lists.opensuse.org http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00020.html
packetstormsecurity.com http://packetstormsecurity.com/files/153218/Exim-4.9.1-Remote-Command-Execution.html
packetstormsecurity.com http://packetstormsecurity.com/files/153312/Exim-4.91-Local-Privilege-Escalation.html
packetstormsecurity.com http://packetstormsecurity.com/files/154198/Exim-4.91-Local-Privilege-Escalation.html
seclists.org http://seclists.org/fulldisclosure/2019/Jun/16
openwall.com http://www.openwall.com/lists/oss-security/2019/06/05/2
openwall.com http://www.openwall.com/lists/oss-security/2019/06/05/3
openwall.com http://www.openwall.com/lists/oss-security/2019/06/05/4
openwall.com http://www.openwall.com/lists/oss-security/2019/06/06/1
openwall.com http://www.openwall.com/lists/oss-security/2019/07/25/6
openwall.com http://www.openwall.com/lists/oss-security/2019/07/25/7
openwall.com http://www.openwall.com/lists/oss-security/2019/07/26/4
openwall.com http://www.openwall.com/lists/oss-security/2021/05/04/7
securityfocus.com http://www.securityfocus.com/bid/108679
bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-10149
seclists.org https://seclists.org/bugtraq/2019/Jun/5
security.gentoo.org https://security.gentoo.org/glsa/201906-01
usn.ubuntu.com https://usn.ubuntu.com/4010-1/
debian.org https://www.debian.org/security/2019/dsa-4456
exim.org https://www.exim.org/static/doc/security/CVE-2019-10149.txt
cisa.gov https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-10149