---
id: "CVE-2019-10149"
kind: "vulnerability"
aliases: ["CVE-2019-10149"]
title: "Exim Mail Transfer Agent (MTA): Exim Mail Transfer Agent (MTA) Improper Input Validation"
severity: "critical"
cvss: 10.0
epss: 0.99961
exploited: true
status: "open"
category: "runtime"
products: [{"name": "Exim Mail Transfer Agent (MTA)", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exim", "exploited", "mail-server", "runtime", "self-hosted"]
not_affected_if: ["managed-hosting", "no-exim-installed"]
published_at: "2019-06-05T14:29:11+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-10149", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2019-10149", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-10149", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Exim Mail Transfer Agent (MTA): Exim Mail Transfer Agent (MTA) Improper Input Validation

Exim, a mail transfer agent that runs on many mail servers, does not properly validate recipient addresses in its delivery code. A remote attacker can send a crafted address to run commands on the server.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Exim Mail Transfer Agent (MTA) affected ? fixed ?

## Fix

Apply the Exim update that addresses CVE-2019-10149 per vendor instructions (CISA KEV required action); the fixed version is not stated in the sources.

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-10149
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2019-10149
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2019-10149

## From the sources

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

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_