CVE-2026-43920 FOSSBilling: Unauthenticated update patcher endpoint allows remote maintenance execution
Unauthenticated attackers can trigger privileged maintenance operations via the /run-patcher endpoint, causing denial of service and data modification.
- 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-2026-43920?
CVE-2026-43920 is a medium-severity missing authorization vulnerability in FOSSBilling, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
FOSSBilling is a free, open-source billing and client management system. In versions 0.5.4 through 0.7.2, the /run-patcher maintenance endpoint in FOSSBilling was accessible without authentication, which allowed unauthenticated remote users to trigger update patch routines that modify configuration files, execute database schema changes, perform filesystem mutations, and clear caches. The /run-patcher endpoint executes privileged maintenance operations - configuration migrations, database patch execution (including ALTER TABLE, DROP TABLE, UPDATE statements), filesystem deletions and renames, and cache clearing - without requiring administrator authentication, CSRF validation, or CLI context. An unauthenticated remote attacker can trigger these operations by sending a simple HTTP GET request to /run-patcher, which can be abused for denial-of-service attacks. Certain patches (e.g., batch token regeneration for all admin and client accounts in patch 53, and session invalidation) are disruptive even when re-executed against an already-patched instance. Repeated or concurrent requests may also cause inconsistent database state. This issue has been fixed in version 0.8.0.
Weakness: CWE-306
Which versions are affected by CVE-2026-43920?
How do I fix CVE-2026-43920?
No fix has been published for CVE-2026-43920 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-2026-43920 being exploited?
There is no known exploitation of CVE-2026-43920 in the wild and no public exploit code.
Sources
Also known as GHSA-prx6-m547-rfmg.