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

Source: https://junglewise.ai/threats/cve-2019-10149-exim-mail-transfer-agent-mta-improper-input-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-01-10. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2019-10149 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2022-01-10

A flaw in the Exim Mail Transfer Agent (MTA) involves improper validation of recipient addresses in the deliver_message() function within /src/deliver.c. This vulnerability can allow a remote attacker to execute arbitrary commands on the host.

Vendors: [Exim](https://junglewise.ai/threats/vendors/exim).

## Quick answers

**Is CVE-2019-10149 exploited in the wild?** Yes. CVE-2019-10149 is known to be exploited in the wild, first recorded on 10 January 2022. Treat it as urgent.

**How severe is CVE-2019-10149?** Critical severity, with a CVSS score of 9.8, published 10 January 2022.

**Which products and versions are affected?** Exim Exim 4.87 to 4.91 (inclusive).

**Is there a fix for CVE-2019-10149?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2019-10149 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2019-10149?** Check whether you run Exim Mail Transfer Agent (MTA). Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Exim Exim 4.87 to 4.91 (inclusive)

## Timeline

- 2019-06-05: disclosed: Initial public disclosure via mailing lists.
- 2022-01-10: kev added: Added to CISA Known Exploited Vulnerabilities Catalog.