HTML Injection Vulnerability in MailerUp by Maalfer
CVE-2026-75872

6.9MEDIUM

Key Information:

Vendor

Maalfer

Status
Mailerup
Vendor
CVE Published:
18 August 2026

What is CVE-2026-75872?

MailerUp prior to version 1.1.3 has a vulnerability that enables unauthenticated remote attackers to inject arbitrary HTML through the first_name field in the public subscription form. This flaw can be exploited to manipulate the content of the double opt-in verification email, allowing attackers to send messages to any chosen address while disguising the sender as the form owner, thereby compromising user security and email integrity.

Affected Version(s)

MailerUp 0 < 1.1.3

References

https://github.com/maalfer/mailerup/commit/da4aedc9621911...
patch
https://github.com/maalfer/mailerup/releases/tag/v1.1.3
release-notes
https://secur0.com/en/cna/cve-list/cve-2026-75872-html-in...
technical-description

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Nacho GarcĂ­a Egea
XoĂĄn M. Otero Jorge
Secur0 CNA
Mario Álvarez Fernåndez
.