Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-27084

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Deserialization of Untrusted Data vulnerability in ThemeREX Buisson buisson allows Object Injection.This issue affects Buisson: from n/a through <= 1.1.11.

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 · moderate confidence

A deserialization of untrusted data vulnerability (Object Injection) in the ThemeREX Buisson WordPress theme allows attackers to inject malicious PHP objects via unserialize() on user-controlled data, potentially leading to remote code execution if POP chains exist in the application.

MitigationUpgrade to the latest version of Buisson theme immediately. Until a patched version is available, disable the theme or implement input validation/sanitization on all data passed to unserialize() functions.

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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Verify ThemeREX Buisson plugin presence
    Locate the plugin directory in the WordPress installation (typically wp-content/plugins/) or check via WordPress admin panel under Plugins > Installed Plugins. Confirm the plugin files exist and the plugin is activated.
    Affected if if the ThemeREX Buisson plugin is installed and activated on the WordPress site
  2. Determine installed plugin version
    Open the main plugin PHP file (usually trx_buisson.php or similar in the plugin directory) and locate the version constant or header comment. Alternatively, check the plugin metadata via WordPress admin or the readme.txt file.
    Affected if if the version cannot be determined or matches known vulnerable versions (compare against any published affected version ranges)
  3. Identify deserialization entry points
    Review the plugin source code for unserialize() function calls handling user-supplied input. Search for parameters that accept serialized data (e.g., $_GET, $_POST, $_REQUEST) passed to unserialize(). Common locations include AJAX handlers, shortcode callbacks, or theme customizer processing.
    Affected if if the plugin contains unserialize() calls processing external input without prior validation
  4. Check exposure of vulnerable endpoint
    Determine if the identified deserialization entry point is accessible without authentication. Test the suspected parameter by submitting a minimal serialized payload or by reviewing access control settings in the plugin. Check for any security-related plugin configuration that may restrict access.
    Affected if if the deserialization handler is accessible to unauthenticated users (remote attack vector exists)
  5. Audit for exploitation indicators
    Review web server access logs for suspicious requests containing serialized PHP data patterns (e.g., O: length:). Examine the uploads directory and wp-content for unexpected PHP files. Check database for unauthorized content or modifications.
    Affected if if logs show serialized data submissions or unexpected files/scripts exist on the server

The environment is affected if the ThemeREX Buisson plugin is installed with a vulnerable version that exposes an unauthenticated unserialize() entry point processing user input.

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

Upgrade to the latest version of Buisson theme immediately. Until a patched version is available, disable the theme or implement input validation/sanitization on all data passed to unserialize() functions.

Recommended fix Moderate confidence

Latest available version of ThemeREX Buisson theme (newer than 1.1.11)

  1. 1. Log in to the WordPress admin dashboard
  2. 2. Navigate to Appearance > Themes
  3. 3. Locate the ThemeREX Buisson theme
  4. 4. Check if an updated version is available in the WordPress theme repository or from ThemeREX
  5. 5. If an updated version is available, install and activate it
  6. 6. If no update is available from official sources, consider: a) using an alternative theme, or b) implementing web application firewall rules to block PHP object injection attempts
Caveat Review theme customizations after upgrade as template changes may affect site appearance

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2026-27084 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
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  • Version or environment caveats, and links to real fixes
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