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CVE-2026-3475

MEDIUM 5.3 CVSS 3.1
Published
March 19, 2026
Last modified
June 17, 2026
NVD status
Deferred
Reported by
security@wordfence.com
Weakness
CWE-862
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Description

The Instant Popup Builder plugin for WordPress is vulnerable to Unauthenticated Arbitrary Shortcode Execution in all versions up to and including 1.1.7. This is due to the handle_email_verification_page() function constructing a shortcode string from user-supplied GET parameters (token, email) and passing it to do_shortcode() without properly sanitizing square bracket characters, combined with missing authorization checks on the init hook. While sanitize_text_field() and esc_attr() are applied, neither function strips or escapes square bracket characters ([ and ]). WordPress's shortcode regex uses [^\]\/]* to match content inside shortcode tags, meaning a ] character in the token value prematurely closes the shortcode tag. This makes it possible for unauthenticated attackers to inject and execute arbitrary registered shortcodes by crafting a malicious token parameter containing ] followed by arbitrary shortcode syntax.

Affected WordPress components

  • Instant Popup Builder – Popup Maker for Videos, Forms, Offers, Announcements, Galleries & More Plugin · instant-popup-builder
    Confirmed match Active
    Up to and including 1.1.7
    View on WordPress.org

A confirmed match is backed by the plugin or theme slug. A possible match is based on the product name only and should be verified.

Affected products and versions

  • instantpopupbuilder Instant Popup Builder – Powerful Popup Maker for Opt-ins, Email Newsletters & Lead Generation — Up to and including 1.1.7

References

  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/instant-popup-builder/tags/1.1.6/public/class-instant-popup-subscription-public.php#L1761
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/instant-popup-builder/tags/1.1.6/public/class-instant-popup-subscription-public.php#L1772
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/instant-popup-builder/trunk/public/class-instant-popup-subscription-public.php#L1761
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/browser/instant-popup-builder/trunk/public/class-instant-popup-subscription-public.php#L1772
  • plugins.trac.wordpress.org https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3477334%40instant-popup-builder&new=3477334%40instant-popup-builder&sfp_email=&sfph_mail=
  • www.wordfence.com https://www.wordfence.com/threat-intel/vulnerabilities/id/979962e3-9052-4dc9-94d0-3ec8de3d5460?source=cve
  • nvd.nist.gov Official NVD record