How to fix CVE-2025-54001?

Within 24 hours: Identify all systems running Classter <= 2.5 and isolate affected instances from production networks if possible; notify stakeholders of the exposure. Within 7 days: Implement WAF rules to block malicious serialized object payloads, disable Classter functionality if non-critical, and deploy input validation controls. Within 30 days: Upgrade to Classter > 2.5 immediately upon patch release, or migrate to alternative solutions if patching timeline is uncertain.

Is Deserialization affected by CVE-2025-54001?

A critical object injection vulnerability (CVE-2025-54001, CVSS 9.8) exists in ThemeREX Classter versions 2.5 and earlier, allowing attackers to execute arbitrary code through deserialization of untrusted data.

CVE-2025-54001

CRITICAL

2026-03-05 [email protected]

9.8

CVSS 3.1

CVSS Vector

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:06 vuln.today

CVE Published

Mar 05, 2026 - 06:16 nvd

CRITICAL 9.8

Description

Deserialization of Untrusted Data vulnerability in ThemeREX Classter classter allows Object Injection.This issue affects Classter: from n/a through <= 2.5.

Analysis

Deserialization of untrusted data in Classter (classter) WordPress theme allows PHP Object Injection, potentially enabling remote code execution through POP chains.

Technical Context

CWE-502 deserialization of untrusted data in classter. Attacker-controlled data is passed to unserialize(), enabling instantiation of arbitrary PHP objects.

Affected Products

['Classter WordPress theme']

Remediation

Update the theme. Avoid unserialize() on user input.

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +0.1

CVSS: +49

POC: 0

CVE-2025-54001 vulnerability details – vuln.today

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CVE-2025-54001

CVSS Vector

Lifecycle Timeline

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Description

Analysis

Technical Context

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CVE-2025-54001

CVSS Vector

Lifecycle Timeline

Tags

Description

Analysis

Technical Context

Affected Products

Remediation

Priority Score

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External POC / Exploit Code