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

CVE-2026-4801

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 Page Builder Gutenberg Blocks – CoBlocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via external iCal feed data in all versions up to, and including, 3.1.16 due to insufficient output escaping of event titles, descriptions, and locations fetched from external iCal feeds in the Events block rendering function. 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 CoBlocks WordPress plugin up to version 3.1.16 contains a stored XSS vulnerability in its Events block. The plugin fails to properly escape event titles, descriptions, and locations fetched from external iCal feeds before rendering them in HTML. Authenticated attackers with Contributor-level access can inject malicious scripts via crafted iCal data that execute when users view affected event pages.

MitigationUpdate to the latest version of CoBlocks when released. Until then, restrict Contributor-level access to the Events block, validate/sanitize iCal feed data server-side before rendering, or implement Content Security Policy headers.

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. Confirm CoBlocks plugin is installed
    In WordPress admin, go to Plugins > Installed Plugins and locate CoBlocks. Note the installed version number.
    Affected if CoBlocks plugin is installed and version is 3.1.16 or lower
  2. Check if Events block is in use
    Review pages, posts, or widgets that contain the CoBlocks Events block. Search for 'coblocks/events' or 'coblocks-event' in the database wp_posts table or use a site search for the block.
    Affected if The Events block is present on any published content
  3. Identify configured iCal feeds
    Edit any page/post containing the Events block and check if an external iCal feed URL is configured in the block settings. Alternatively, search the database for iCal URLs in postmeta where meta_key contains 'coblocks' and meta_value contains 'http' or '.ics'.
    Affected if An external iCal feed URL is connected to any Events block on the site
  4. Inspect stored event data for injected scripts
    Query the wp_posts and wp_postmeta tables for event entries from iCal feeds. Look for script tags, javascript: URIs, onload/onerror attributes, or other XSS patterns in title, description, or location fields.
    Affected if Any event data contains unsanitized HTML or script injection attempts
  5. Verify user role permissions
    Review user roles on the site. Go to Users > All Users and check if any users have the Contributor role, as Contributors can access the Events block.
    Affected if Contributor-level users exist and have access to create or edit content with the Events block

The environment is affected if CoBlocks version 3.1.16 or lower is installed, the Events block is in use with an iCal feed configured, and Contributors can access content editing capabilities.

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 to the latest version of CoBlocks when released. Until then, restrict Contributor-level access to the Events block, validate/sanitize iCal feed data server-side before rendering, or implement Content Security Policy headers.

Recommended fix High confidence

CoBlocks version 3.1.17 or higher

  1. 1. Log in to the WordPress admin dashboard
  2. 2. Navigate to Plugins > Installed Plugins
  3. 3. Locate the CoBlocks (Page Builder Gutenberg Blocks – CoBlocks) plugin
  4. 4. If an update is available, click 'Update Now' to update to the latest version
  5. 5. Alternatively, download the latest version from wordpress.org/plugins/coblocks/ and upload via Plugins > Add New > Upload Plugin
  6. 6. After updating, verify the plugin version is 3.1.17 or higher
  7. 7. Test the Events block functionality to ensure the iCal feed import still works correctly
Caveat No breaking changes expected; this is a security patch release

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2026-4801 in production — separate from our analysis above.

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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
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