The AMP Enhancer plugin allows stored cross‑site scripting through the AMP Custom CSS setting. Insufficient input sanitization and output escaping enable an authenticated attacker with Administrator‑level access or higher to inject arbitrary JavaScript that will be executed whenever a page containing the custom CSS is viewed by a user. This flaw is a classic input‑validation weakness classified as CWE‑79.

WordPress installations that use AMP Enhancer version 1.0.49 or earlier, specifically in multi‑site configurations or where the unfiltered_html capability has been disabled. Any site that grants Administrator privileges to a user can be used to inject malicious payloads into the custom CSS field.

The CVSS score of 4.4 indicates moderate severity, while the EPSS score of less than 1 % reflects a very low probability of active exploitation at present. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires authenticated access with Administrator or higher privileges and the ability to modify the AMP Custom CSS setting; once injected, the script will execute for all visitors to the affected pages.