dbcve.org
Missing AuthorizationWeakness · CWE-862

CVE-2026-3475

MEDIUM · 5.3 CVSS v3.1 Published 2026-03-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Instant Popup Builder plugin for WordPress has an unauthenticated arbitrary shortcode execution vulnerability in the handle_email_verification_page() function. The function uses user-supplied GET parameters (token, email) directly in do_shortcode() calls without removing square brackets. While sanitize_text_field() and esc_attr() are applied, they don't strip [ or ] characters, allowing attackers to inject arbitrary shortcodes by closing the shortcode tag early with ] and appending malicious shortcode syntax.

MitigationUpdate to a patched version of the plugin if available; otherwise, disable the plugin until a fix is released. Alternatively, implement input sanitization to strip or properly escape square bracket characters before passing to do_shortcode().

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Instant Popup Builder plugin is installed
    Navigate to WordPress admin > Plugins and verify 'Instant Popup Builder' is listed as an active or installed plugin
    Affected if The plugin appears in the installed plugins list
  2. Identify the plugin version
    Check the plugin's main PHP file (usually in wp-content/plugins/instant-popup-builder/) for the 'Version' header, or check the plugin details in the WordPress plugins admin page
    Affected if The installed version is unknown, older, or not yet patched against this vulnerability
  3. Verify the handle_email_verification_page function exists
    Inspect the plugin's main PHP file(s) and search for the function 'handle_email_verification_page' or 'do_shortcode' calls within it
    Affected if The vulnerable function exists and contains do_shortcode() calls using GET parameters (token, email)
  4. Check if email verification page is publicly accessible
    Attempt to access the verification endpoint (typically includes 'email_verification' or similar in the URL path) without authentication
    Affected if The page is accessible to unauthenticated users and accepts GET parameters
  5. Inspect how GET parameters are processed
    Review the plugin code to confirm that GET parameters 'token' and/or 'email' are passed to do_shortcode() without stripping square brackets [ and ]
    Affected if Square brackets are not removed from user-supplied input before being used in do_shortcode()

A user is affected if the Instant Popup Builder plugin is installed, the handle_email_verification_page function exists with vulnerable do_shortcode() usage, and the email verification page is accessible without authentication.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update to a patched version of the plugin if available; otherwise, disable the plugin until a fix is released. Alternatively, implement input sanitization to strip or properly escape square bracket characters before passing to do_shortcode().

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-3475 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data