CVE-2026-4125 WPMK Block <= 1.0.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes
Authenticated attackers can inject arbitrary scripts via shortcode attributes, leading to code execution in victim browsers.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-4125?
CVE-2026-4125 is a medium-severity cross-site scripting vulnerability in wpmkorg WPMK Block, published on 22 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The WPMK Block plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'class' shortcode attribute in all versions up to and including 1.0.1. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes. Specifically, in the wpmk_block_shortcode() function, the 'class' attribute is extracted from user-controllable shortcode attributes and directly concatenated into an HTML div element's class attribute without any escaping (e.g., esc_attr()). 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-4125?
How do I fix CVE-2026-4125?
No fix has been published for CVE-2026-4125 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-2026-4125 being exploited?
There is no known exploitation of CVE-2026-4125 in the wild and no public exploit code.
Sources
Also known as GHSA-f4p3-578m-v245.