CVE-2026-29204 Missing authorization in WHMCS
Authenticated users can access or modify other users' addon data by manipulating addonId parameters due to missing ownership checks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-29204?
CVE-2026-29204 is a critical missing authorization vulnerability in WebPros WHMCS, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-639
Which versions are affected by CVE-2026-29204?
How do I fix CVE-2026-29204?
No fix has been published for CVE-2026-29204 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-29204 being exploited?
There is no known exploitation of CVE-2026-29204 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-5j8p-mmp9-6fj8.