CVE-2026-75872Network attack vector

HTML email injection via unescaped first_name

Published Aug 18, 2026 · Updated Aug 18, 2026

HTML injection in the public subscription form in Maalfer MailerUp before 1.1.3 allows remote attackers to send crafted HTML emails. In backend/apps/forms/views.py, _send_verification_email and _verification_email_html place the subscription request's first_name into the double opt-in email body without HTML escaping, and the same template also trusted unvalidated form title and color values before 1.1.3. No authentication is required because POST /subscribe// is public; exploitation lets an attacker direct a message to an attacker-chosen recipient from the form owner's configured sending identity, with message-content integrity impact rather than server-side code execution.

CVSS severity6.9
Medium
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTML injection in the public subscription form in Maalfer MailerUp before 1.1.3 allows remote attackers to send crafted HTML emails. In backend/apps/forms/views.py, _send_verification_email and _verification_email_html place the subscription request's first_name into the double opt-in email body without HTML escaping, and the same template also trusted unvalidated form title and color values before 1.1.3. No authentication is required because POST /subscribe// is public; exploitation lets an attacker direct a message to an attacker-chosen recipient from the form owner's configured sending identity, with message-content integrity impact rather than server-side code execution.

The record

CVE
CVE-2026-75872
Published
Aug 18, 2026
Updated
Aug 18, 2026
Vendor
Maalfer
Product
MailerUp
Classifications
CWE-80, T1566
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Maalfer · MailerUpversion=0 <1.1.3

Published CVSS scores

6.9Secur0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
T1566Phishing

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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