CVE-2026-4561 Cross-site scripting in MC4WP: Mailchimp for WordPress
Authenticated attackers with Author access can inject arbitrary scripts via form response messages, leading to stored XSS execution on victim pages.
- 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-2026-4561?
CVE-2026-4561 is a medium-severity cross-site scripting vulnerability in dvankooten MC4WP: Mailchimp for WordPress, published on 22 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the form response message post meta fields (e.g., 'text_subscribed', 'text_error') in all versions up to, and including, 4.12.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-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-2026-4561?
How do I fix CVE-2026-4561?
No fix has been published for CVE-2026-4561 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-2026-4561 being exploited?
There is no known exploitation of CVE-2026-4561 in the wild and no public exploit code.
Sources
Also known as GHSA-fm8w-hq2c-rg96.