What is CVE-2023-5621?

CVE-2023-5621 is a medium-severity vulnerability in I13websolution Thumbnail Slider With Lightbox, classified under Cross-site Scripting. CVSS score: 4.4/10. Published 2023-10-18.

How severe is CVE-2023-5621?

Medium severity. CVSS v3 base score is 4.4 out of 10.

Is CVE-2023-5621 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in I13websolution Thumbnail Slider With Lightbox

CVE-2023-5621

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-10-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (31.6th percentile), scored 2026-09-28.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 31.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

I13websolution Thumbnail Slider With Lightbox — versions 1.0
Nik00726 Thumbnail Slider With Lightbox — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

20142995/nuclei-templates

References

www.wordfence.com/threat-intel/vulnerabilities/id/547c425d-8b0f-4e65-8b8a-c3a30… (Third Party Advisory)
wordpress.org/plugins/wp-responsive-slider-with-lightbox/ (Product)
plugins.trac.wordpress.org/changeset (Product)

Frequently asked questions

What is CVE-2023-5621?: CVE-2023-5621 is a medium-severity vulnerability in I13websolution Thumbnail Slider With Lightbox, classified under Cross-site Scripting. CVSS score: 4.4/10. Published 2023-10-18.
How severe is CVE-2023-5621?: Medium severity. CVSS v3 base score is 4.4 out of 10.
Is CVE-2023-5621 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.