CVE-2026-3604 - WP SEO Structured Data Schema <= 2.8.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via '_kcseo_ative_tab' Parameter

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MEDIUM

WP SEO Structured Data Schema <= 2.8.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via '_kcseo_ative_tab' Parameter

Published May 12, 2026

4.9

MEDIUM

CVSS 3.1

EPSS 0.29%

Description

The WP SEO Structured Data Schema plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `_kcseo_ative_tab` parameter in all versions up to, and including, 2.8.1 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.

Affected products

Vendor Kcseopro Product WP SEO Structured Data Schema Default
unaffected
- Version
  0
  Status
  affected
  Constraints
  <=2.8.1

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Kcseopro

WP SEO Structured Data Schema

unaffected

Version	Status	Constraints
0	affected	<=2.8.1

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-79

Cross-site Scripting (XSS)

References (6)

Link	Providers	Tags
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-29391		Advisory
https://plugins.trac.wordpress.org/browser/wp-seo-structured-data-schema/tags/2.8.1/lib/classes/KcSeoMetaData.php#L133
https://plugins.trac.wordpress.org/browser/wp-seo-structured-data-schema/tags/2.8.1/lib/classes/KcSeoMetaData.php#L177
https://plugins.trac.wordpress.org/browser/wp-seo-structured-data-schema/trunk/lib/classes/KcSeoMetaData.php#L133
https://plugins.trac.wordpress.org/browser/wp-seo-structured-data-schema/trunk/lib/classes/KcSeoMetaData.php#L177
https://www.wordfence.com/threat-intel/vulnerabilities/id/315fbc93-5af3-4fe9-b97a-a09957e54c97?source=cve