Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-54001

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-05
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 Classter classter allows Object Injection.This issue affects Classter: from n/a through <= 2.5.

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 PHP Object Injection vulnerability exists in the ThemeREX Classter WordPress theme (versions <= 2.5) due to unsafe deserialization of untrusted data. The vulnerability allows attackers to inject malicious PHP objects, potentially leading to remote code execution if suitable 'gadget chains' exist within the application or loaded libraries.

MitigationReplace any unsafe unserialize() calls with secure alternatives like json_decode() for data that originates from user input, implement strict input validation, and update to a patched version if available from ThemeREX.

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. Confirm ThemeREX Classter theme is installed
    Navigate to wp-content/themes/ and check for a folder named 'classter' or 'trx_classter'. Alternatively, go to WordPress Admin > Appearance > Themes and verify the Classter theme is active or installed.
    Affected if The ThemeREX Classter theme is present in the WordPress installation.
  2. Determine the installed theme version
    Check the style.css file in the theme folder for the 'Version:' header, or view the theme details in WordPress Admin > Appearance > Themes. Compare the version number to the affected range (versions <= 2.5).
    Affected if The installed version is 2.5 or lower.
  3. Locate unsafe unserialize() calls in theme files
    Search the theme directory for PHP files containing 'unserialize(' by using a command like 'grep -r "unserialize(" wp-content/themes/classter/' or a file content search tool. Examine the context of each occurrence to determine if untrusted user input is passed to unserialize().
    Affected if The theme contains unserialize() calls that process data from user input (e.g., $_GET, $_POST, $_COOKIE, or database values that can be controlled by users).
  4. Identify potential gadget chains
    Search for class definitions within the theme and any bundled libraries that might be used as gadget chains. Look for magic methods like __wakeup, __destruct, __toString, or __call that could be chained to achieve code execution. Review loaded Composer or other library dependencies.
    Affected if The application contains classes with exploitable magic methods that could form a gadget chain for object injection.

A user is affected if the ThemeREX Classter theme version is 2.5 or lower AND the theme uses unserialize() on untrusted user-controlled data with exploitable gadget chains present in the codebase.

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

Replace any unsafe unserialize() calls with secure alternatives like json_decode() for data that originates from user input, implement strict input validation, and update to a patched version if available from ThemeREX.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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Scan for this in your stack

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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-2025-54001 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
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  • Version or environment caveats, and links to real fixes
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