XSS in Kcseopro Wp Seo Structured Data Schema

CVE-2026-3604

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (19.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-3604: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-3604?
CVE-2026-3604 is a medium-severity vulnerability in Kcseopro Wp Seo Structured Data Schema, classified under Cross-site Scripting. CVSS score: 4.9/10. Published 2026-05-12.
How severe is CVE-2026-3604?
Medium severity. CVSS v3 base score is 4.9 out of 10.