The Logo Slider – Logo Carousel, Logo Showcase & Client Logo Slider Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the image alt text in all versions up to, and including, 4.9.0 due to insufficient input sanitization and output escaping in the 'logo-slider' shortcode. 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.