# 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.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-f324-cf3c-hqgv

## 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 (Improper Neutralization of Input During Web Page Generation)

## 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.

## Is CVE-2026-4300 being exploited?

There is no known exploitation of CVE-2026-4300 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4300 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-4300 in the wild and no public exploit code.

Affected product: robosoft Robo Gallery – Photo & Image Slider. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-4300/ (Markdown: https://insights.sbomify.com/CVE-2026-4300/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4300
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4300
- OSV: https://osv.dev/vulnerability/CVE-2026-4300

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-4300/
Summaries are generated and may contain mistakes; the official description above is the record.