Insufficient Session Expiration in GitHub repository fossbilling/fossbilling prior to 0.5.5.

FOSSBilling is a free, open-source billing and client management system. Versions 0.6.10 through 0.7.2 have a PHP code injection vulnerability in FOSSBilling's Config::prettyPrintArrayToPHP() method. When configuration values are updated, string values are written into config.php without escaping single quotes. Because config.php is loaded via a bare include on every HTTP request, an attacker with admin privileges can inject arbitrary PHP code that executes on every subsequent request. Version 0.8.0 contains a patch. Some workarounds are available. Restrict admin access to trusted personnel only; audit config.php for unexpected PHP code; and/ or at the reverse proxy/WAF level, restrict access to admin API endpoints that modify configuration.

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, when a client or staff/admin account is suspended or marked inactive, existing authenticated sessions are not invalidated. The session identity loaders in src/di.php (loggedinclient and loggedinadmin) only reject sessions if the backing account record no longer exists in the database. They do not verify that the account's status is still active. This allows a suspended or deactivated user to retain full access until their session naturally expires. This issue has been fixed in version 0.8.0.

FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 allow a low-privileged staff account to grant arbitrary module permissions to itself through the admin API, resulting in persistent privilege escalation. A staff user that only has staff.createandeditstaff can call /api/admin/staff/permissionsupdate targeting their own account and write any permission structure, bypassing the intended role-based access control boundary. Version 0.8.0 patches the issue. Some workarounds are available. Restrict the staff.createandeditstaff permission to only highly trusted staff members and/or use a reverse proxy or WAF to restrict access to /api/admin/staff/permissionsupdate to specific trusted roles.

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Guest API invoice/update endpoint is missing an authorization check present in other invoice-related endpoints, allowing an unauthenticated user with knowledge of an invoice hash to modify the payment gateway associated with an unpaid invoice. An attacker who obtains an invoice hash, which may leak through shared URLs, referrer headers, or email links, can change the gatewayid on an unpaid invoice to any payment gateway configured in the system. This does not allow redirecting payments to an arbitrary external endpoint, as the gateway must already be installed and configured by an administrator. The practical impact is further limited by the invoiceaccessiblefromhash system setting. Version 0.8.0 contains a patch. No known workarounds are available.

FOSSBilling is a free, open-source billing and client management system. In versions 0.5.6 through 0.7.2, when a ClientPasswordReset record already exists for a client (from a previous unexpired reset request), subsequent calls to the resetpassword guest API endpoint reuse the existing token instead of generating a new one. The 15-minute validity window is anchored to the first request's createdat timestamp, not the time of the most recent email. An attacker who obtained the original reset link remains able to use it even after the victim requests a new reset, because the original token is never invalidated or rotated. Version 0.8.0 patches the issue. Some workarounds are available. Configure a reverse proxy (e.g., Nginx, Apache, Cloudflare) to apply per-IP rate limiting to the /client/reset-password endpoint to minimize the window of opportunity, and/or manually clear expired clientpasswordreset records from the database after a client reports a suspected compromise.

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.