Vulnerabilidad · Publicado 08/10/2026
Se ha identificado una vulnerabilidad (CVE-2026-107577, CVSS 7.5) en Progressive Robot hMailServer versiones 6.0.0 a 6.3.5 que permite a atacantes remotos no autenticados causar indisponibilidad del servicio de correo. La falla radica en ineficiencia algorítmica y bucles infinitos al procesar encabezados MIME malformados en mensajes recibidos. Afecta directamente a servidores de correo en empresas de México y LATAM que dependan de esta plataforma.
Inefficient algorithmic complexity and a non-terminating loop in the MIME processing of received messages in Progressive Robot hMailServer 6.0.0 through 6.3.5 allow a remote unauthenticated attacker to make the mail services unavailable by sending a message. Removing a MIME header parameter whose value is empty and directly followed by a semicolon (for example a Content-Disposition with 'filename=a.bat; filename=;') entered a loop that never terminates, holding a worker thread at full load until the server is restarted; this is reached when the attachment blocker renames a blocked attachment or a filename is set over the REST API. Separately, decoding a header field that holds many RFC 2047 encoded words of an encoding other than base64 or quoted-printable, removing a parameter with many RFC 2231 continuations, and deleting many header fields of one name each took time growing with the square of the message, on the small thread pools that serve IMAP, SMTP and POP3 connections, delivery and the REST API.
Score: 7.5/10 — Severidad: HIGH — Estado NIST: Received
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-835
Publicado en NIST NVD.