What’s Vulnerable › Vulnerabilities

CVE-2026-75872: HTML Injection in MailerUp double opt-in verification email

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-18 · updated 2026-10-22
• Weakness: CWE-80

Description

HTML Injection in the public subscription form in maalfer MailerUp before 1.1.3 allows unauthenticated remote attackers to have the application send a message carrying arbitrary HTML, to an attacker-chosen address and from the form owner's configured sending identity, via the first_name field of the subscription request, which is interpolated unescaped into the double opt-in verification email.

Affected products

• maalfer MailerUp: before 1.1.3 — fixed in 1.1.3

How to fix

Upgrade to a fixed version: maalfer MailerUp 1.1.3. Check the vendor advisory for mitigations.

References

• https://github.com/maalfer/mailerup/commit/da4aedc9621911df4ce0cc8f0b321dd6d10f40a5
• https://github.com/maalfer/mailerup/releases/tag/v1.1.3
• https://secur0.com/en/cna/cve-list/cve-2026-75872-html-injection-in-mailerup-double-optin-verification-email

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