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

CVE-2026-0894

MEDIUM · 6.4 CVSS v3.1 Published 2026-04-18
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 Content Blocks (Custom Post Widget) plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's content_block shortcode in all versions up to, and including, 3.3.9 due to insufficient input sanitization and output escaping on user supplied values consumed from user-created content blocks. 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 Content Blocks plugin for WordPress contains a stored XSS vulnerability in the content_block shortcode handler. The plugin fails to properly sanitize and escape user-supplied values within content blocks, allowing authenticated users with contributor-level permissions or higher to inject malicious JavaScript that executes when other users view affected pages.

MitigationUpdate the plugin to a version beyond 3.3.9 once a patch is released, or implement proper input sanitization using WordPress sanitization functions and output escaping via esc_html() or esc_attr() on all user-supplied values rendered through the shortcode.

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 Content Blocks plugin is installed
    Go to WordPress admin > Plugins and check if the Content Blocks plugin appears in the installed plugins list. Note the installed version displayed in the plugin details.
    Affected if The plugin is present in the WordPress installation
  2. Check the installed plugin version
    In the plugins list, locate the Content Blocks plugin and record the version number shown. Compare this version against the affected range (versions up to and including 3.3.9).
    Affected if The installed version is 3.3.9 or lower
  3. Identify use of the content_block shortcode
    Search the WordPress database or site content (posts, pages, widgets) for the [content_block] shortcode tag. Use phpMyAdmin or WP-CLI: wpdb get_results("SELECT * FROM wp_posts WHERE post_content LIKE '%[content_block%'")
    Affected if The shortcode is present in any published content
  4. Inspect shortcode output for proper escaping
    View a page containing the content_block shortcode in the browser. View the page source and check if user-supplied attributes (such as title, content, or custom fields) are wrapped in esc_html() or esc_attr() or similar escaping functions. Alternatively, grep the plugin files for the shortcode handler and verify it uses functions like esc_html, esc_attr, or sanitize_text_field on attribute values.
    Affected if User-supplied values in the shortcode output are not escaped with esc_html/esc_attr
  5. Review user roles with contributor-level access
    In WordPress admin > Users, list all users and their roles. Identify any users assigned the Contributor, Author, Editor, or Administrator role, as these roles allow shortcode usage.
    Affected if There are users with Contributor, Author, Editor, or Administrator roles who can edit content containing the shortcode

The environment is affected if the Content Blocks plugin version is 3.3.9 or lower, the content_block shortcode is in use, and at least one user with contributor-level or higher permissions exists on the site.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update the plugin to a version beyond 3.3.9 once a patch is released, or implement proper input sanitization using WordPress sanitization functions and output escaping via esc_html() or esc_attr() on all user-supplied values rendered through the shortcode.

Recommended fix Moderate confidence

Content Blocks (Custom Post Widget) plugin version 3.4.0 or later

  1. 1. Update the Content Blocks (Custom Post Widget) WordPress plugin to version 3.4.0 or later
  2. 2. After updating, verify that the plugin functions correctly on the site
  3. 3. Review existing content blocks for any malicious scripts that may have been injected by compromised contributor-level accounts
  4. 4. Audit user accounts with contributor-level and above permissions to ensure no unauthorized access occurred

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-0894 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data