CVE-2026-28496
CriticalCVSS 9.4Summary
FOSSBilling prior to version 0.8.0 has a Server-Side Template Injection (SSTI) vulnerability in the template rendering system. Administrators can inject arbitrary Twig expressions, leading to information disclosure and remote code execution.
Risk Assessment
This vulnerability poses a serious security risk to the organization, allowing attackers to access sensitive data and potentially execute code remotely on the server.
Recommendation
It is recommended to upgrade to version 0.8.0, audit existing email templates for suspicious Twig expressions, and block external access to /api/system/* at reverse proxy/WAF.
Original NVD description (English source)
FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 have a Server-Side Template Injection (SSTI) vulnerability in the template rendering system. Administrators with access to features that render Twig templates (email templates, mass mail campaigns, custom payment adapters, and the `string_render` API endpoint) can inject arbitrary Twig expressions, leading to information disclosure and remote code execution. The vulnerability exists because Twig templates are rendered without a sandbox, allowing access to the full Twig environment, API context, and the application's dependency injection container. Version 0.8.0 patches the issue. Some workarounds are available. Audit existing email templates for suspicious Twig expressions, rotate all admin and client API tokens, and/or block external access to /api/system/* at reverse proxy/WAF to mitigate chaining with GHSA-78x5-c8gw-8279.