CVE-2026-4329 Blackhole for Bad Bots <= 3.8 - Unauthenticated Stored Cross-Site Scripting via User-Agent HTTP Header
Unauthenticated attackers can inject scripts via User-Agent headers that execute when admins view the plugin's log page, potentially leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-4329?
CVE-2026-4329 is a high-severity cross-site scripting vulnerability in specialk Blackhole for Bad Bots, published on 26 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-4329?
How do I fix CVE-2026-4329?
No fix has been published for CVE-2026-4329 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-4329 being exploited?
There is no known exploitation of CVE-2026-4329 in the wild and no public exploit code.
Sources
Also known as GHSA-cpmh-vq2q-hhp7.