CVE-2026-4329: Blackhole for Bad Bots <= 3.8 - Unauthenticated Stored Cross-Site Scripting via User-Agent HTTP Header

Description

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

Low

Integrity

Low

Availability

None

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.3% · higher than 25% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

BF

Blackhole for Bad Bots · specialk

through 3.8 · source: vendor