CVE-2026-18742
Flatsome <= 3.20.12 - Authenticated (Contributor+) DOM-Based Stored Cross-Site Scripting via 'data-text-sec', 'data-title', and 'title' Attributes via Custom HTML Block
- Medium 6.4
Description
The Flatsome theme for WordPress is vulnerable to Stored Cross-Site Scripting via 'data-text-sec', 'data-title', and 'title' Attributes via Custom HTML Block in all versions up to, and including, 3.20.12 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. The payload survives server-side sanitization because wp_kses_post permits data-* attributes globally via _wp_add_global_attributes, allowing attacker-controlled values in data-text-sec, data-title, and title attributes to persist in saved post content and be later interpreted as HTML by the ux-countdown, scroll-to, and lightbox-gallery JavaScript behaviors.
Key facts
- Published
- 14 Nov 2026
- Last changed
- 14 Nov 2026
- Assigned by
- Wordfence
- EPSS
- 0.19% likely to be exploited in the next 30 days, higher than 8.694% of CVEs (scores for 15 Nov 2026)
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 6.4CVSS 3.1, Mediumfrom the CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| UX-themes | Flatsome |
|
Timeline
- 13 Nov 2026 Disclosed
- 14 Nov 2026 Published
Weakness
Practice this bug class
HackZoneLabs has a hands-on lab on XSS (stored, reflected, DOM) (CWE-79).