dbcve.org
Unrestricted File UploadWeakness · CWE-434

CVE-2026-5411

HIGH · 8.8 CVSS v3.1 Published 2026-06-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
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 WP Captcha PRO (the premium version of the Advanced Google reCAPTCHA plugin, both have the same slug) plugin for WordPress is vulnerable to arbitrary file upload in all versions up to, and including, 5.38. This is due to a capability check in the save_ajax() function of the licensing module, combined with unrestricted file extraction in sync_cloud_protection(). This makes it possible for authenticated attackers, with Subscriber-level access and above, to upload arbitrary files including PHP webshells to the server by injecting a malicious cloud_protection_url into the license meta, which the plugin then downloads and extracts without file type validation into a web-accessible uploads directory. This can be used for remote code execution. Note: The vulnerability can only be exploited with a remote URL if "allow_url_fopen" is enabled in the php.ini config.

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 WP Captcha PRO (and free Advanced Google reCAPTCHA) WordPress plugin has an arbitrary file upload vulnerability. Authenticated users with Subscriber-level access can inject a malicious cloud_protection_url into license metadata via the save_ajax() function. The sync_cloud_protection() function then downloads and extracts files from this URL without any file type validation into a web-accessible directory, allowing PHP webshell upload and remote code execution.

MitigationUpdate to plugin version 5.39 or later to receive the security patch. As a workaround, disable allow_url_fopen in php.ini and consider removing or restricting the plugin until an update is 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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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. Check installed plugin version
    Navigate to WordPress admin > Plugins > Installed Plugins, locate 'WP Captcha PRO' or 'Advanced Google reCAPTCHA', and note the version number displayed. Compare this to version 5.39 (the patched release).
    Affected if Installed version is lower than 5.39 and the plugin is active.
  2. Confirm plugin is active
    In WordPress admin, verify the plugin is currently activated. The vulnerability only applies to an active plugin installation.
    Affected if The plugin is active and version is below 5.39.
  3. Identify subscriber-level users
    Go to WordPress admin > Users and review the user list. Note any users assigned the 'Subscriber' role, as this level has sufficient privileges to exploit the vulnerability via the save_ajax() function.
    Affected if Any Subscriber-level user accounts exist on the site.
  4. Inspect plugin directories for suspicious files
    Using file manager or SSH, examine the wp-content/plugins/captcha-pro/ directory (or similar path for Advanced Google reCAPTCHA) and the wp-content/uploads/ directory for unexpected .php files with random names, webshells, or recently uploaded files that do not match expected plugin behavior.
    Affected if Unknown PHP files are present in plugin or upload directories, especially with recent modification dates.
  5. Check for exploitation artifacts
    Review server access logs for POST requests to /wp-admin/admin-ajax.php with action 'cptch_save_ajax' or similar, and look for patterns indicating sync_cloud_protection() was triggered with suspicious URLs.
    Affected if AJAX requests to save_ajax action contain unusual or external URLs in request parameters.

A user is affected if they are running WP Captcha PRO or Advanced Google reCAPTCHA plugin versions below 5.39, the plugin is active, and subscriber-level users exist 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.

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

Update to plugin version 5.39 or later to receive the security patch. As a workaround, disable allow_url_fopen in php.ini and consider removing or restricting the plugin until an update is available.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,440
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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-2026-5411 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