CVE-2026-29204

CRITICAL

WHMCS 7.4.0-18.12.1, 18.13.0-18.13.2, 9.0.0-9.0.3 - Authorization Bypass via clientarea.php addonId

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-29204. PoCs published by bogdanrotariu.

AI-analyzed exploit summary This repository provides a detailed technical analysis and mitigation for CVE-2026-29204, an authorization bypass in WHMCS where a logged-in client can access foreign addon contexts via crafted requests. It includes a temporary hook-based guard to block unauthorized access and logs such attempts.

Description

Insufficient ownership check in `clientarea.php` allows an authenticated client area user to submit requests using another user’s `addonId` without any ownership validation leading to unauthorized access to the victim's account.

Exploits (1)

nomisec WRITEUP
by bogdanrotariu · poc
https://github.com/bogdanrotariu/cve-2026-29204-whmcs-clientarea-addonid

This repository provides a detailed technical analysis and mitigation for CVE-2026-29204, an authorization bypass in WHMCS where a logged-in client can access foreign addon contexts via crafted requests. It includes a temporary hook-based guard to block unauthorized access and logs such attempts.

Classification
Writeup 95%
Attack Type
Auth Bypass
Complexity
Moderate
Reliability
Reliable
Target: WHMCS (versions prior to 8.13.3 and 9.0.4)
Auth required
Prerequisites: Logged-in client session · Access to the `clientarea.php` endpoint with `action=productdetails` and `modop=custom`
devstral-2 · analyzed May 13, 2026 Full analysis →

References (1)

Core 1

Scores

CVSS v3 9.1
EPSS 0.0005
EPSS Percentile 15.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-639
Status published
Products (3)
WebPros/WHMCS 18.13.0 - 18.13.3
WebPros/WHMCS 7.4.0 - 18.12.2
WebPros/WHMCS 9.0.0 - 9.0.4
Published May 12, 2026
Tracked Since May 13, 2026