XSS in Specialk Blackhole For Bad Bots

CVE-2026-4329

The Blackhole for Bad Bots plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the User-Agent HTTP header in all versions up to and including 3.8. This is due to insufficient input sanitization and output escaping. The plugin uses sanitize_text_field() when capturing bot data (which strips HTML tags but does not escape HTML entities like double quotes), then stores the data via update_option(). When an administrator views the Bad Bots log page, the stored data is output directly into HTML input value attributes (lines 75-83) without esc_attr() and into HTML span content without esc_html(). This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute when an administrator views the Blackhole Bad Bots admin page.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (41.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.3% 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-2026-4329: held from 0.003 to 0.005.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-4329?
CVE-2026-4329 is a high-severity vulnerability in Specialk Blackhole For Bad Bots, classified under Cross-site Scripting. CVSS score: 7.2/10. Published 2026-03-26.
How severe is CVE-2026-4329?
High severity. CVSS v3 base score is 7.2 out of 10.