CVE
UX-themes Flatsome stored XSS in custom HTML block attributes
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.19% · 8th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 14/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Flatsome, a WordPress theme from UX-themes, has a stored cross-site scripting flaw in several HTML attributes that can be set through the Custom HTML block. An attacker with contributor-level access or higher can reach it remotely, and the injected script runs in the browser of any user who opens the affected page.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Original 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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity6.4/10CVSS 6.4
- No patch5/5No patch listed yet
What would change the score
- Would score about 69 if added to CISA KEV
- Would score about 64 if CISA's SSVC rates exploitation active
- Would score about 33 if advisories confirm default setups are exposed
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-18742 (Flatsome <= 3.20.12 - Authenticated (Contributor+) DOM-Based Stored Cross-Site Scripting via 'data-text-sec', 'data-title', and 'title'…), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-18742 (entry last updated 2026-11-14):
Affected:
- UX-themes Flatsome: through 3.20.12
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-18742 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-18742 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://www.wordfence.com/threat-intel/vulnerabilities/id/d6567c87-9e69-4e18-bea3-08d8aae23ef6?source=cve
- https://themeforest.net/item/flatsome-multipurpose-responsive-woocommerce-theme/5484319#item-description__change-log
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-18742
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-18742"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- UX-themes Flatsome
through 3.20.12
Evidence 4
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-18742
Is CVE-2026-18742 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-18742?
Flatsome: through 3.20.12.Source: cve.now feed data