Email Testing Tool Vulnerability in Mailpit by Axllent

CVE-2026-67447

What is CVE-2026-67447?

Mailpit, an email testing tool developed by Axllent, has a vulnerability that allows unauthenticated SMTP clients to send oversized data lines, exceeding the permitted MaxMessageSize. This flaw stems from the improper size check implemented in the readData() function. Consequently, an attacker could exploit this by sending a line that is larger than the configured size, leading to substantial memory pressure as Mailpit allocates resources beyond set limits before it can reject the input. The issue affects versions 1.30.0 through 1.30.5 and has been resolved in version 1.30.5.

References