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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 10 Jan 2022, 950 days after the CVE record was published.

How likely is exploitation in the next 30 days?

100%

EPSS score, percentile 100 of all scored records

How severe?

9.0 Critical

CVSS v3.0 base score, given by the CNA

What should I do?

CISA deadline 10 Jul 2022. Apply updates per vendor instructions.

Advisories and patches (4)

Which versions are affected?

Affected

• 4.92

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 10 July 2022.

Advisories and patches

• USN-4010-1 (Vendor advisory)
• DSA-4456 (Vendor advisory)
• GLSA-201906-01 (Vendor advisory)
• openSUSE-SU-2019:1524 (Vendor advisory)

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2019-10149

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Improper validation of recipient address in deliver_message() function in /src/deliver.c may lead to remote command execution.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2019-10149 to its Known Exploited Vulnerabilities (KEV) catalog on 10 Jan 2022.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 10 Jul 2022.
• The CVE record was published on 5 Jun 2019, 950 days before it was added to KEV.
• The CVE record carries a CVSS v3.0 base score of 9.0 (Critical), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 100% (percentile 100), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

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: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-78

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• 108679 (Vulnerability database)
• [oss-security] 20190605 Re: CVE-2019-10149: Exim 4.87 to 4.91: possible remote exploit
• [oss-security] 20190605 Re: CVE-2019-10149: Exim 4.87 to 4.91: possible remote exploit
• [oss-security] 20190605 Re: CVE-2019-10149: Exim 4.87 to 4.91: possible remote exploit
• 20190605 [SECURITY] [DSA 4456-1] exim4 security update
• [oss-security] 20190606 Re: CVE-2019-10149: Exim 4.87 to 4.91: possible remote exploit
• 20190611 The Return of the WIZard: RCE in Exim (CVE-2019-10149)
• [oss-security] 20190725 Re: Statistics for distros lists updated for 2019Q2

8 more in the CVE record.

More exploited Exim vulnerabilities

• CVE-2010-4344: Exim Heap-Based Buffer Overflow Vulnerability (added 25 Mar 2022)
• CVE-2010-4345: Exim Privilege Escalation Vulnerability (added 25 Mar 2022)
• CVE-2019-16928: Exim Out-of-bounds Write Vulnerability (added 3 Mar 2022)
• CVE-2018-6789: Exim Buffer Overflow Vulnerability (added 3 Nov 2021)