Vulnerability · Published Aug 18, 2026 · Assigned by Secur0

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

Medium 6.9

In plain English

A medium-severity security flaw in MailerUp from maalfer. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 55% of all known vulnerabilities).

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.7%top 45.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
maalfer	MailerUp	0 – before 1.1.3

Weakness: CWE-80 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

References

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