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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-4125

MEDIUM · 6.4 CVSS v3.1 Published 2026-04-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The WPMK Block plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'class' shortcode attribute in all versions up to and including 1.0.1. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes. Specifically, in the wpmk_block_shortcode() function, the 'class' attribute is extracted from user-controllable shortcode attributes and directly concatenated into an HTML div element's class attribute without any escaping (e.g., esc_attr()). 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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The WPMK Block WordPress plugin fails to sanitize and escape the 'class' shortcode attribute in the wpmk_block_shortcode() function. The attribute is directly concatenated into an HTML div's class attribute without using escape functions like esc_attr(), allowing authenticated attackers with Contributor-level access to inject arbitrary JavaScript that executes in victim browsers.

MitigationApply input sanitization using functions like esc_attr() to the 'class' attribute before output, or update to a patched version of the plugin once available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify WPMK Block plugin is installed
    Navigate to WordPress Admin > Plugins and check if 'WPMK Block' appears in the installed plugins list
    Affected if The plugin is installed and active in the WordPress environment
  2. Determine the installed plugin version
    In Plugins list, look for the version number under the WPMK Block plugin name, or check the plugin header in /wp-content/plugins/wpmk-block/wpmk-block.php
    Affected if The version cannot be confirmed as patched (no patched version information available)
  3. Identify usage of the wpmk_block shortcode
    Search WordPress database or content for occurrences of the [wpmk_block] shortcode: query posts table for meta_value containing 'wpmk_block' or search post content for the shortcode pattern
    Affected if The shortcode is present in any post, page, or custom post type content
  4. Check if contributor-level users can edit content
    Navigate to Users > All Users in WordPress admin and verify if any users exist with the 'Contributor' role, or check Roles under Users > Roles
    Affected if At least one Contributor-level user account exists in the WordPress site
  5. Inspect the vulnerable source code
    Locate the wpmk_block_shortcode() function in the plugin file (typically /wp-content/plugins/wpmk-block/inc/shortcode.php or similar) and check if the 'class' attribute is wrapped with esc_attr() before output
    Affected if The code does NOT use esc_attr() or similar escaping on the class parameter before outputting it into the HTML div class attribute

A user is affected if the WPMK Block plugin is installed with an unpatched version, the wpmk_block shortcode is in use, and contributor-level users exist who could inject malicious scripts through the class attribute.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply input sanitization using functions like esc_attr() to the 'class' attribute before output, or update to a patched version of the plugin once available.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-4125 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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