# CVE-2023-5621: Thumbnail Slider With Lightbox <= 1.0 - Authenticated (Administrator+) Stored Cross-Site Scripting via Image Title

> Administrators can inject arbitrary scripts via image titles in this WordPress plugin, affecting multi-site or restricted HTML configurations.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Oct 2023
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-7c84-qx75-c25g

## What is CVE-2023-5621?

CVE-2023-5621 is a medium-severity cross-site scripting vulnerability in nik00726 Thumbnail Slider With Lightbox, published on 18 Oct 2023. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

The Thumbnail Slider With Lightbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Image Title field in versions up to, and including, 1.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2023-5621?

It affects 1 product.


Products: I13websolution Thumbnail Slider With Lightbox.

## How do I fix CVE-2023-5621?

No fix has been published for CVE-2023-5621 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-5621 being exploited?

There is no known exploitation of CVE-2023-5621 in the wild and no public exploit code.

## Other vulnerabilities in nik00726 Thumbnail Slider With Lightbox

- [CVE-2023-5820](https://insights.sbomify.com/CVE-2023-5820/): Cross-site request forgery in Thumbnail Slider With Lightbox (critical 9.6)
- [CVE-2015-10146](https://insights.sbomify.com/CVE-2015-10146/): Thumbnail Slider With Lightbox <= 1.0.4 - Authenticated (Admin+) SQL Injection (medium 4.9)
- [CVE-2023-5531](https://insights.sbomify.com/CVE-2023-5531/): Thumbnail Slider With Lightbox <= 1.0 - Cross-Site Request Forgery (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-5621 and fix it if it is affected.

What it is: CVE-2023-5621 is a medium-severity cross-site scripting vulnerability in nik00726 Thumbnail Slider With Lightbox, published on 18 Oct 2023. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-5621 in the wild and no public exploit code.

Affected product: nik00726 Thumbnail Slider With Lightbox. 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-2023-5621/ (Markdown: https://insights.sbomify.com/CVE-2023-5621/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-5621
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-5621
- OSV: https://osv.dev/vulnerability/CVE-2023-5621

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-5621/
Summaries are generated and may contain mistakes; the official description above is the record.