Strong Testimonials: Stored XSS through testimonial lightbox classes
The Strong Testimonials plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'lightbox_class' Shortcode Attribute in all versions up to, and including, 3.3.8 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires that the targeted testimonial view has at least one published testimonial with a featured image and the lightbox wrapper enabled, as the vulnerable code path is only reached when a thumbnail is rendered. The image and lightbox requirements are essential; the export does not name the submission route or rendering function. Affected versions reported by the CNA: <= 3.3.8.
- Component
- Strong Testimonials
- Plugin slug
strong-testimonials- Affected
- <= 3.3.8
- Safe version
- See mitigation notes
- Published
- Sep 18, 2026
This CVE was published Sep 18, 2026 and is one of 21 known issues for this plugin.
Update, patch or deactivate.
This archive could not verify a fixed version from the official author release notes reviewed on 2026-10-13. Disable the affected feature or component where practical until remediation for the deployed configuration is established. Allowlist lightbox class tokens and escape the final attribute; remove injected saved content. Disable lightbox rendering or restrict testimonial editing until updated. Official author release notes: https://wordpress.org/plugins/strong-testimonials/.
No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical description
The Strong Testimonials plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'lightbox_class' Shortcode Attribute in all versions up to, and including, 3.3.8 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires that the targeted testimonial view has at least one published testimonial with a featured image and the lightbox wrapper enabled, as the vulnerable code path is only reached when a thumbnail is rendered.
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N