CVE-2026-18488
Received Received - Intake

Stored XSS in Blocksy Companion WordPress Plugin

Publication date: 2026-09-01

Last updated on: 2026-09-01

Assigner: Wordfence

Description
The Blocksy Companion plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'tagName' Block Attribute (blocksy/dynamic-data) in all versions up to, and including, 2.1.51 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with author-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

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Meta Information

Published
2026-09-01
Last Modified
2026-09-01
Generated
2026-09-01
AI Q&A
2026-09-01
EPSS Evaluated
N/A
NVD
CVE-2026-18488
EUVD
EUVD-2026-68987

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
blocksy blocksy_companion to 2.1.51 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

The Blocksy Companion WordPress plugin has a stored Cross-Site Scripting (XSS) vulnerability in versions up to 2.1.51. It allows authenticated attackers with author-level access or higher to inject malicious scripts via the 'tagName' block attribute due to insufficient input sanitization and output escaping.

Detection Guidance

Check for the Blocksy Companion plugin versions up to and including 2.1.51. Inspect WordPress sites for unauthorized script injections in pages or posts, particularly via the 'tagName' block attribute. Review user roles with author-level access or higher for suspicious activity.

Impact Analysis

An attacker could inject scripts that execute when users access modified pages, potentially stealing user sessions, redirecting to malicious sites, or defacing the website. Requires author-level access or higher to exploit.

Compliance Impact

This vulnerability could lead to unauthorized data access or modification, violating GDPR (data protection) and HIPAA (health data privacy) by exposing sensitive user information through script injection.

Mitigation Strategies

Update the Blocksy Companion plugin to the latest version beyond 2.1.51. Remove or restrict author-level and higher user roles to only trusted individuals. Scan WordPress sites for existing malicious scripts and remove them.

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