CVE-2026-23829

Mailpit is an email testing tool and API for developers. Prior to version 1.28.3, Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\r` and `\n` when used inside a character class. Version 1.28.3 fixes this issue.
Configurations

Configuration 1 (hide)

cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*

History

17 Jun 2026, 10:22

Type Values Removed Values Added
Summary
  • (es) Mailpit es una herramienta de pruebas de correo electrónico y una API para desarrolladores. Antes de la versión 1.28.3, el servidor SMTP de Mailpit era vulnerable a la inyección de encabezados debido a una expresión regular insuficiente utilizada para validar las direcciones `RCPT TO` y `MAIL FROM`. Un atacante puede inyectar encabezados SMTP arbitrarios (o corromper los existentes) incluyendo caracteres de retorno de carro ("\r") en la dirección de correo electrónico. Esta inyección de encabezados se produce porque la expresión regular destinada a filtrar los caracteres de control no excluye "\r" y "\n" cuando se utiliza dentro de una clase de caracteres. La versión 1.28.3 corrige este problema.
References () https://github.com/axllent/mailpit/security/advisories/GHSA-54wq-72mp-cq7c - Exploit, Third Party Advisory, Mitigation () https://github.com/axllent/mailpit/security/advisories/GHSA-54wq-72mp-cq7c - Exploit, Mitigation, Third Party Advisory

23 Feb 2026, 17:29

Type Values Removed Values Added
CPE cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*
First Time Axllent mailpit
Axllent
References () https://github.com/axllent/mailpit/commit/36cc06c125954dec6673219dafa084e13cc14534 - () https://github.com/axllent/mailpit/commit/36cc06c125954dec6673219dafa084e13cc14534 - Patch
References () https://github.com/axllent/mailpit/releases/tag/v1.28.3 - () https://github.com/axllent/mailpit/releases/tag/v1.28.3 - Product, Release Notes
References () https://github.com/axllent/mailpit/security/advisories/GHSA-54wq-72mp-cq7c - () https://github.com/axllent/mailpit/security/advisories/GHSA-54wq-72mp-cq7c - Exploit, Third Party Advisory, Mitigation

19 Jan 2026, 19:16

Type Values Removed Values Added
Summary (en) Mailpit is an email testing tool and API for developers. Prior to version 1.28. Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\r` and `\n` when used inside a character class. Version 1.28.3 fixes this issue. (en) Mailpit is an email testing tool and API for developers. Prior to version 1.28.3, Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\r` and `\n` when used inside a character class. Version 1.28.3 fixes this issue.

19 Jan 2026, 00:15

Type Values Removed Values Added
New CVE

Information

Published : 2026-01-19 00:15

Updated : 2026-06-17 10:22


NVD link : CVE-2026-23829

Mitre link : CVE-2026-23829

CVE.ORG link : CVE-2026-23829


JSON object : View

Products Affected

axllent

  • mailpit
CWE
CWE-93

Improper Neutralization of CRLF Sequences ('CRLF Injection')

CWE-150

Improper Neutralization of Escape, Meta, or Control Sequences