CVE-2026-28496

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.

CVSS

No CVSS.

References

Link	Resource
https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-57mv-jm88-66jc
https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-78x5-c8gw-8279
https://www.vulncheck.com/blog/fossbilling-auth-bypass-ssti-rce

Configurations

No configuration.

History

23 Jun 2026, 15:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-23 15:16

Updated : 2026-06-23 16:16

NVD link : CVE-2026-28496

Mitre link : CVE-2026-28496

CVE.ORG link : CVE-2026-28496

JSON object : View

Products Affected

No product.

CWE

CWE-1336

Improper Neutralization of Special Elements Used in a Template Engine

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