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CVE-2024-4045: Popup Builder by OptinMonster – WordPress Popups for Optins, Email Newsletters and Lead Generation <= 2.16.1 - Authenticated (Contributor+) Stored Cross-Site Scripting

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-25 · updated 2026-06-17
• Weakness: CWE-79

Description

The Popup Builder by OptinMonster – WordPress Popups for Optins, Email Newsletters and Lead Generation plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘campaign_id’ parameter in versions up to, and including, 2.16.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Affected products

• OptinMonster: before 2.16.2 — fixed in 2.16.2

How to fix

Upgrade to a fixed version: OptinMonster 2.16.2. Check the vendor advisory for mitigations.

References

• https://plugins.trac.wordpress.org/browser/optinmonster/tags/2.16.0/OMAPI/Elementor/Widget.php#L532
• https://plugins.trac.wordpress.org/changeset/3087905/
• https://www.wordfence.com/threat-intel/vulnerabilities/id/b4dfeb49-38d3-495d-af96-d67a29b339fa?source=cve
• https://plugins.trac.wordpress.org/browser/optinmonster/tags/2.16.0/OMAPI/Elementor/Widget.php#L532
• https://plugins.trac.wordpress.org/changeset/3087905/
• https://www.wordfence.com/threat-intel/vulnerabilities/id/b4dfeb49-38d3-495d-af96-d67a29b339fa?source=cve

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