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

CVE-2026-9838

MEDIUM · 6.1 CVSS v3.1 Published 2026-07-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges 6 weeks old

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 ICS Calendar plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'htmltagtitle' parameter in all versions up to, and including, 12.0.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. The vulnerability is reachable via the unauthenticated wp_ajax_nopriv_r34ics_ajax AJAX action, which accepts attacker-controlled js_args values merged over stored shortcode configuration without nonce verification, allowing the htmltagtitle key to bypass the normal shortcode allowlist check.

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 ICS Calendar WordPress plugin has a Reflected XSS vulnerability in versions up to 12.0.9. The 'htmltagtitle' parameter lacks proper sanitization and output escaping, allowing script injection. The flaw is exploitable via the unauthenticated wp_ajax_nopriv_r34ics_ajax action which accepts attacker-controlled js_args merged over stored shortcode configuration without nonce verification, bypassing normal allowlist checks.

MitigationUpdate to version 12.1.0 or later which includes proper input sanitization, output escaping, and nonce verification for the AJAX action.

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
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 ICS Calendar plugin is installed
    Check WordPress plugins directory for 'ICS Calendar' or inspect the plugin files in wp-content/plugins/ics-calendar/ for the main plugin file
    Affected if Plugin is present in the WordPress installation
  2. Identify installed version number
    Read the main plugin file header (e.g., ics-calendar.php) or check the WordPress plugin admin page to find the Version field
    Affected if Version is 12.0.9 or lower (any version below 12.1.0)
  3. Verify the vulnerable AJAX endpoint exists
    Check if the file containing wp_ajax_nopriv_r34ics_ajax action exists in the plugin; this is typically in an AJAX handler file
    Affected if The AJAX action r34ics_ajax is registered and accessible to unauthenticated users
  4. Check for shortcode usage that includes htmltagtitle parameter
    Search post content, page content, or widget areas for [ics_calendar] shortcode occurrences, specifically looking for htmltagtitle parameter
    Affected if Any shortcode uses the htmltagtitle parameter without proper escaping in output

You are affected if the ICS Calendar plugin is installed with version 12.0.9 or lower AND the vulnerable r34ics_ajax AJAX endpoint is accessible to unauthenticated users.

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 version 12.1.0 or later which includes proper input sanitization, output escaping, and nonce verification for the AJAX action.

Recommended fix Moderate confidence

Update to ICS Calendar version 12.1.0 or later (the first version containing the fix)

  1. Log in to the WordPress admin dashboard
  2. Navigate to Plugins > Installed Plugins
  3. Locate the ICS Calendar plugin
  4. Check the current version (should be 12.0.9 or below if vulnerable)
  5. Click 'Update Now' to install the latest version of ICS Calendar
  6. After updating, verify the plugin is functioning correctly by viewing a page with an ICS Calendar shortcode
  7. Confirm the fix by ensuring the htmltagtitle parameter is properly sanitized

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,600
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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-2026-9838 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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