dbcve.org
Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-1856

MEDIUM · 6.4 CVSS v3.1 Published 2026-06-19
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 Appointment Booking Calendar plugin for WordPress is vulnerable to Stored Cross-Site Scripting via custom booking field labels in all versions up to, and including, 1.4.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Author-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 Appointment Booking Calendar WordPress plugin versions up to 1.4.4 fail to properly sanitize and escape custom booking field labels, allowing authenticated users with Author-level permissions or higher to inject malicious JavaScript code. This stored XSS executes whenever users access pages containing the affected booking fields.

MitigationUpdate the plugin to a version beyond 1.4.4 that includes proper input sanitization (e.g., sanitize_text_field) and output escaping (e.g., esc_html, esc_attr) for all custom field labels. Immediately revoke or audit accounts with Author-level access if not actively used.

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. Identify if Appointment Booking Calendar plugin is installed
    Locate the plugin directory in WordPress (typically wp-content/plugins) or access it via WordPress admin under Plugins > Installed Plugins. Look for 'Appointment Booking Calendar' or similar naming.
    Affected if The plugin is present in the WordPress installation
  2. Determine the installed plugin version
    In WordPress admin, go to Plugins > Installed Plugins and locate the Appointment Booking Calendar entry. The version number is displayed below the plugin name. Alternatively, check the main plugin PHP file for a 'Version:' header comment.
    Affected if The version is 1.4.4 or any version up to 1.4.4 (e.g., 1.3.0, 1.4.0, 1.4.3)
  3. Check for existing custom booking field labels
    Navigate to the plugin's settings where custom booking fields are configured (typically under Appointments > Fields or a similar menu item). Inspect the existing field labels for any unexpected HTML, script tags, or JavaScript code.
    Affected if Any custom field label contains script tags, event handlers (onclick, onerror, etc.), or suspicious encoded content
  4. Verify if Author-level accounts exist
    In WordPress admin, go to Users > All Users and review the role column. Identify accounts assigned the Author role or higher that are not actively used or are untrusted.
    Affected if There are Author-level or higher users who did not create the custom fields but have access to the plugin's field configuration

A user is affected if the Appointment Booking Calendar plugin is installed at version 1.4.4 or below AND any custom booking field labels contain unsanitized script content, regardless of whether the injecting user is legitimate.

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 1.4.4 that includes proper input sanitization (e.g., sanitize_text_field) and output escaping (e.g., esc_html, esc_attr) for all custom field labels. Immediately revoke or audit accounts with Author-level access if not actively used.

Recommended fix High confidence

Version 1.4.5 or later (any version after 1.4.4)

  1. Log in to WordPress admin dashboard
  2. Navigate to Plugins > Installed Plugins
  3. Find 'Appointment Booking Calendar' plugin
  4. Click 'Update Now' to update to the latest version, or manually update to version 1.4.5 or higher if automatic update is not available
  5. Verify the update completed successfully

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
  • Testing2.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,780
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,848.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-1856 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2026-1856 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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