# CVE-2026-43925: FOSSBilling mass assignment in client self-registration

Source: https://junglewise.ai/threats/cve-2026-43925-fossbilling-mass-assignment-in-client-self-registration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-06. Updated: 2026-07-06  
License: CC BY 4.0 with a link back

CVE-2026-43925 · Severity: info · CVSS 6.9 · Published 2026-07-06

FOSSBilling, an open-source billing and client management platform, contains a flaw in its user registration process. An attacker can exploit this to assign themselves to restricted customer groups, such as 'Staff' or 'Resellers', without authorization. This allows the attacker to use exclusive discount codes and obtain services at unauthorized lower prices, potentially leading to financial loss for the service provider.

Technologies: [FOSSBilling](https://junglewise.ai/threats/technologies/fossbilling). Vendors: [FOSSBilling](https://junglewise.ai/threats/vendors/fossbilling).

## Quick answers

**Is CVE-2026-43925 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-43925 being exploited in the wild.

**How severe is CVE-2026-43925?** Informational severity, with a CVSS score of 6.9, published 6 July 2026.

**Which products and versions are affected?** FOSSBilling 0.1.0 to 0.7.2.

**Is there a fix for CVE-2026-43925?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-43925 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-43925?** Check whether you run FOSSBilling at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A mass assignment vulnerability exists in the guestCreateClient() handler within src/modules/Client/Service.php. The application fails to filter the input data before passing it to the internal createClient() method, which unconditionally assigns the 'group_id' parameter to the new user record. An unauthenticated attacker can exploit this by including a 'group_id' field in their POST request to the /api/guest/client/create endpoint. By joining a privileged group, the attacker bypasses eligibility checks in the promo code system, enabling the use of restricted discounts. This issue is resolved in version 0.8.0.

## Affected products

- FOSSBilling FOSSBilling 0.1.0 to 0.7.2

## Timeline

- 2026-06-04: advisory: GitHub Security Advisory published
- 2026-07-06: disclosed: NVD publication date

## References

- [https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-q4rq-9844-r9w2](https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-q4rq-9844-r9w2)

## Related threats

- [FOSSBilling stored XSS in support ticket notes](https://junglewise.ai/threats/cve-2026-111048-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling CSRF vulnerability in staff guest login endpoint](https://junglewise.ai/threats/cve-2026-112374-fossbilling-before-0-8-9-contains-a-cross-site-request-forgery)
- [FOSSBilling email enumeration via guest signup endpoint](https://junglewise.ai/threats/cve-2026-111056-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling path traversal in template_exists endpoint](https://junglewise.ai/threats/cve-2026-111053-fossbilling-is-an-open-source-billing-and-client-management)
- [FOSSBilling authorization bypass in extension configuration management](https://junglewise.ai/threats/cve-2026-111046-fossbilling-is-an-open-source-billing-and-client-management)