CVE-2026-8623 Dear Flipbook <= 2.4.30 - Authenticated (Contributor+) Stored Cross-Site Scripting via '.dvcss' Element Class Attribute
Authenticated contributors can inject arbitrary scripts via CSS class attributes in the Dear Flipbook WordPress plugin, leading to stored XSS.
- 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-2026-8623?
CVE-2026-8623 is a medium-severity cross-site scripting vulnerability in dearhive DearFlip – PDF Flipbook, 3D Flipbook, PDF embed, PDF viewer, published on 5 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Dear Flipbook – PDF Flipbook, 3D Flipbook, PDF embed, PDF viewer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'post_content (class attribute of .dvcss element)' parameter in all versions up to, and including, 2.4.30 due to insufficient input sanitization and output escaping. 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. The payload is embedded as a Base64-encoded JSON object in a CSS class name on a Custom HTML block; the frontend parseCSSElements() function decodes it client-side with atob() and JSON.parse() and renders the logo property as raw HTML, meaning no server-side or client-side sanitization intercepts the malicious script before DOM insertion.
Weakness: CWE-79
Which versions are affected by CVE-2026-8623?
How do I fix CVE-2026-8623?
No fix has been published for CVE-2026-8623 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-2026-8623 being exploited?
There is no known exploitation of CVE-2026-8623 in the wild and no public exploit code.
Sources
Also known as GHSA-35hh-c4h4-vp3q.