CVE-2026-67399

Received Received - Intake

Deserialization Flaw in WHMCS Allows Code Execution

Publication date: 2026-09-14

Last updated on: 2026-09-14

Assigner: HackerOne

Description

Deserialization of untrusted data in WHMCS 9.0.0 before 9.0.8 and 8.0.0 before 8.13.7 allows remote attackers to execute arbitrary code.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-14

Last Modified

2026-09-14

Generated

2026-09-15

AI Q&A

2026-09-15

EPSS Evaluated

N/A

NVD

CVE-2026-67399

Affected Vendors & Products

Vendor	Product	Version / Range
whmcs	whmcs	to 9.0.8 (exc)
whmcs	whmcs	to 8.13.7 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-502	The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Attack-Flow Graph

Executive Summary

This vulnerability involves deserialization of untrusted data in WHMCS versions before 9.0.8 and 8.0.0 before 8.13.7. Attackers can exploit this to execute arbitrary code remotely.

Impact Analysis

Remote attackers can execute arbitrary code on affected systems, potentially leading to full system compromise, data theft, or further network infiltration.

Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, violating GDPR (data protection) and HIPAA (health information security) compliance requirements.

Mitigation Strategies

Update WHMCS to version 9.0.8 or later if using 9.0.0, or to 8.13.7 or later if using 8.0.0. Remove untrusted data deserialization in affected versions.

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