VDB-403768 · CVE-2026-67399 · GCVE-0-2026-67399

WebPros WHMCS up to 8.13.6/9.0.7 deserialization

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.0	$0-$5k	0.00+

Summaryinfo

A vulnerability categorized as critical has been discovered in WebPros WHMCS up to 8.13.6/9.0.7. This affects an unknown part. Executing a manipulation can lead to deserialization. This vulnerability appears as CVE-2026-67399. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in WebPros WHMCS up to 8.13.6/9.0.7. This vulnerability affects an unknown functionality. The manipulation with an unknown input leads to a deserialization vulnerability. The CWE definition for the vulnerability is CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at help.whmcs.com. This vulnerability was named CVE-2026-67399 since 07/29/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available.

Upgrading to version 8.13.7 or 9.0.8 eliminates this vulnerability.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

WebPros

Name

WHMCS

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Deserialization
CWE: CWE-502 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: WHMCS 8.13.7/9.0.8

Timelineinfo

07/29/2026 CVE reserved
09/14/2026 +47 days Advisory disclosed
09/14/2026 +0 days VulDB entry created
09/14/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: help.whmcs.com
Status: Confirmed

CVE: CVE-2026-67399 (🔒)
GCVE (CVE): GCVE-0-2026-67399
GCVE (VulDB): GCVE-100-403768

Entryinfo

Created: 09/14/2026 23:14
Changes: 09/14/2026 23:14 (65)
Complete: 🔍
Cache ID: 216::103