CVE-2026-43921: 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::prettyPrint
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-43921
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-439210.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 19% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-43921 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for FOSSBilling is a
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- unknownCVE-2026-53648: FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.…nvd · 2026-07-07
- unknownCVE-2026-53647: FOSSBilling is a free, open-source billing and client management system. In versions 0.5.3 thr…nvd · 2026-07-07
- unknownCVE-2026-53646: FOSSBilling is a free, open-source billing and client management system. In versions 0.5.6 thr…nvd · 2026-07-06
- unknownCVE-2026-53645: FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8…nvd · 2026-07-06
- unknownCVE-2026-53644: FOSSBilling is a free, open-source billing and client management system. Versions 0.5.3 throug…nvd · 2026-07-06
- unknownCVE-2026-53643: FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8…nvd · 2026-07-06
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