CVE-2026-4300 Robo Gallery <= 5.1.3 - Authenticated (Author+) Stored Cross-Site Scripting via 'Loading Label' Setting
Authenticated attackers with Author access can inject arbitrary JavaScript via the Loading Label setting, leading to stored XSS execution on frontend 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-2026-4300?
CVE-2026-4300 is a medium-severity cross-site scripting vulnerability in robosoft Robo Gallery – Photo & Image Slider, published on 8 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
The Robo Gallery plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'Loading Label' setting in all versions up to, and including, 5.1.3. The plugin uses a custom `|***...***|` marker pattern in its `fixJsFunction()` method to embed raw JavaScript function references within JSON-encoded configuration objects. When a gallery's options are rendered on the frontend, `json_encode()` wraps all string values in double quotes. The `fixJsFunction()` method then strips the `"|***` and `***|"` sequences, effectively converting a JSON string value into raw JavaScript code. The Loading Label field (stored as `rbs_gallery_LoadingWord` post_meta) is an `rbstext` type field that is sanitized with `sanitize_text_field()` on save. While this strips HTML tags, it does not strip the `|***...***|` markers since they contain no HTML. When a user inputs `|***alert(document.domain)***|`, the value passes through sanitization intact, is stored in post_meta, and is later retrieved and output within an inline `<script>` tag via `renderMainBlock()` with the quote markers stripped — resulting in arbitrary JavaScript execution. The gallery post type uses `capability_type => 'post'`, allowing Author-level users to create galleries. 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 a page containing the gallery shortcode.
Weakness: CWE-79
Which versions are affected by CVE-2026-4300?
How do I fix CVE-2026-4300?
No fix has been published for CVE-2026-4300 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-2026-4300 being exploited?
There is no known exploitation of CVE-2026-4300 in the wild and no public exploit code.
Sources
Also known as GHSA-f324-cf3c-hqgv.