Deserialization Vulnerability in WHMCS by WHMCS Limited
CVE-2026-67399

9.3CRITICAL

Key Information:

Vendor

Webpros

Status
Whmcs
Vendor
CVE Published:
14 September 2026

What is CVE-2026-67399?

A deserialization vulnerability in WHMCS prior to versions 9.0.8 and 8.13.7 allows remote attackers to manipulate untrusted data, potentially leading to arbitrary code execution on affected systems. This flaw underscores the importance of validating input data in applications to mitigate security risks. Users are recommended to update their installations promptly to prevent exploitation.

Affected Version(s)

WHMCS 9.0.0 < 9.0.8

WHMCS 8.0.0 < 8.13.7

References

https://help.whmcs.com/m/125386/l/2118034-cve-2026-67399-...

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

azizk (@realazizk)
.