CVE-2019-10149 — Exim Mail Transfer Agent (MTA) Improper Input Validation

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.

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
exim	exim	4.92

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2022-01-10. Ransomware use: Unknown.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

Open in Sigma generator →

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-06-05T00:00:00.000Z
• Last modified: 2025-10-21T23:45:35.245Z
• Added to CISA KEV: 2022-01-10
• BOD 22-01 due: 2022-07-10

09References

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