# CVE-2026-43920: FOSSBilling missing authentication in /run-patcher endpoint

Source: https://junglewise.ai/threats/cve-2026-43920-fossbilling-missing-authentication-in-run-patcher-endpoint  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-26. Updated: 2026-06-26  
License: CC BY 4.0 with a link back

CVE-2026-43920 · Severity: info · CVSS 6.9 · Published 2026-06-26

FOSSBilling, an open-source billing and client management platform, contains a security flaw where a maintenance tool used for system updates is accessible to anyone on the internet. An attacker can remotely trigger this tool to modify system settings, delete files, or reset database tables without needing a password. This can lead to a total service outage, loss of access for legitimate administrators and clients, and potential corruption of business data.

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

## Quick answers

**Is CVE-2026-43920 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-43920 being exploited in the wild.

**How severe is CVE-2026-43920?** Informational severity, with a CVSS score of 6.9, published 26 June 2026.

**Which products and versions are affected?** FOSSBilling 0.5.4 - 0.7.2.

**Is there a fix for CVE-2026-43920?** A patch was published on 2026-05-28: Version 0.8.0 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-43920 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-43920?** 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 missing authentication check (CWE-306) exists in the 'checkUpdatePatcher()' function within 'src/load.php'. This function is invoked during early application initialization before authentication or CSRF middleware are applied. An unauthenticated remote attacker can trigger the '/run-patcher' endpoint via a simple HTTP GET request. This executes the 'UpdatePatcher' class, which performs privileged operations including database migrations (ALTER/DROP TABLE), configuration writes to 'config.php', and filesystem deletions. While a cache-based guard exists, it can be bypassed after version upgrades or cache clears, leading to denial-of-service or inconsistent database states. The issue is resolved in version 0.8.0.

## Affected products

- FOSSBilling FOSSBilling 0.5.4 - 0.7.2

## Timeline

- 2026-05-28: patched: Version 0.8.0 released
- 2026-06-12: advisory: GitHub Security Advisory published
- 2026-06-26: disclosed: CVE-2026-43920 published to NVD

## References

- [https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0](https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0)
- [https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-prx6-m547-rfmg](https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-prx6-m547-rfmg)

## 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)