What is the CVSS score of CVE-2025-66571?

CVE-2025-66571 has a CVSS 4.0 base score of 9.3 (Critical). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. EPSS exploitation probability: 0.3%.

Which versions of PHP are affected by CVE-2025-66571?

UNA CMS installations (versions 9.0.0-RC1 through 14.0.0-RC4) are vulnerable to remote code execution attacks by unauthenticated threat actors.

Is there a public PoC exploit available for CVE-2025-66571?

Yes, a public proof-of-concept exploit is available for CVE-2025-66571. Prioritise patching immediately. EPSS: 0.3%.

How to fix or mitigate CVE-2025-66571?

Within 24 hours: Inventory all UNA CMS instances and their versions; isolate affected systems from production networks if possible. Within 7 days: Deploy WAF rules to block requests with serialized PHP objects to the vulnerable endpoint (BxBaseMenuSetAclLevel.php); implement IP whitelisting for administrative interfaces. Within 30 days: Upgrade to patched version when released; establish a vendor patch monitoring process and migration timeline; conduct security audit of affected systems for signs of compromise.

PHP CVE-2025-66571

EUVD-2025-201274 CRITICAL

Deserialization of Untrusted Data (CWE-502)

2025-12-04 disclosure@vulncheck.com

PHP Deserialization

9.3

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

9.3 CRITICAL

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Lifecycle Timeline

EUVD ID Assigned

Mar 15, 2026 - 16:35 euvd

EUVD-2025-201274

Analysis Generated

Mar 15, 2026 - 16:35 vuln.today

PoC Detected

Dec 08, 2025 - 18:27 vuln.today

Public exploit code

CVE Published

Dec 04, 2025 - 21:16 nvd

CRITICAL 9.3

DescriptionCVE.org

UNA CMS versions 9.0.0-RC1 - 14.0.0-RC4 contain a PHP object injection vulnerability in BxBaseMenuSetAclLevel.php where the profile_id POST parameter is passed to PHP unserialize() without proper handling, allowing remote, unauthenticated attackers to inject arbitrary PHP objects and potentially write and execute arbitrary PHP code.

Analysis

Technical ContextAI

Insecure deserialization occurs when untrusted data is used to reconstruct objects, allowing attackers to manipulate serialized data to execute arbitrary code. This vulnerability is classified as Deserialization of Untrusted Data (CWE-502).

RemediationAI

Avoid deserializing untrusted data. Use safe serialization formats (JSON instead of native serialization). Implement integrity checks on serialized data.

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CVE-2025-66571 vulnerability details – vuln.today

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PHP CVE-2025-66571

Severity by source

CVSS VectorNVD

Lifecycle Timeline

DescriptionCVE.org

Analysis

Technical ContextAI

RemediationAI

More from same product – last 7 days

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External POC / Exploit Code