Advanced iFrame <= 2026.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via Gutenberg Block 'additional' Attribute
Description
The Advanced iFrame plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'additional' parameter in all versions up to, and including, 2026.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
CVSS Vector Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:NTechnical Details
<=2026.1Source Code
WordPress.org SVNPatched version not available.
I cannot fulfill your request to provide a detailed exploitation research plan for CVE-2026-6742. I am prohibited from generating actionable exploitation materials, functional payloads, or step-by-step guides for compromising specific software or systems. If you are interested in WordPress security…
Show full research plan
I cannot fulfill your request to provide a detailed exploitation research plan for CVE-2026-6742. I am prohibited from generating actionable exploitation materials, functional payloads, or step-by-step guides for compromising specific software or systems.
If you are interested in WordPress security and defending against similar vulnerabilities, you can research general security practices online. I recommend consulting resources such as:
- The WordPress Developer Handbook: Specifically the sections on "Plugin Security" and "Data Sanitization/Escaping."
- OWASP (Open Web Application Security Project): For comprehensive guides on preventing Stored Cross-Site Scripting (XSS) and implementing secure coding standards.
- The WordPress Plugin Review Team Guidelines: Which outline the security standards required for plugins hosted on the official repository.
These resources provide authoritative information on how to properly sanitize inputs and escape outputs to prevent unauthorized script execution in web applications.
Summary
The Advanced iFrame plugin for WordPress (up to version 2026.1) is vulnerable to Stored Cross-Site Scripting because it fails to properly sanitize and escape the 'additional' attribute within its Gutenberg block implementation. This allows authenticated users with at least Contributor-level permissions to inject malicious scripts into posts, which then execute in the browsers of users viewing the page.
Exploit Outline
An authenticated user with Contributor-level access or higher creates or modifies a post using the Advanced iFrame Gutenberg block. The attacker injects a malicious payload into the 'additional' attribute of the block (e.g., HTML event handlers or script tags). Because the plugin does not properly sanitize this attribute on save or escape it on output, the script is stored in the database and executes in the context of any user viewing the published post.
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