Vulnerability · Published Jun 23, 2026 · Assigned by GitHub_M
CVE-2026-27604FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions
Critical 10.0
In plain English
A critical-severity information exposure in FOSSBilling from FOSSBilling. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.3% (higher than 70% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei.
Official description
FOSSBilling is a free, open-source billing and client management system. Starting in version 0.5.4 and prior to version 0.8.0, an authorization bypass in the API role handling allows unauthenticated access to privileged `/api/system/*` endpoints. Because `system` resolves to the cron admin identity, attackers can invoke admin API methods without valid credentials, session, or CSRF token. Version 0.8.0 patches the issue. Some workarounds are available. Block external access to `/api/system/*` at reverse proxy/WAF, restrict API access by trusted source IPs only (`api.allowed_ips`), rotate all admin/client API tokens immediately, invalidate active sessions and reset high-privilege credentials, and/or review API request logs for suspicious `/api/system/` access and treat as potential incident.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| FOSSBilling | FOSSBilling | >= 0.5.4, < 0.8.0 |
Weakness: CWE-200, CWE-306, CWE-862, CWE-863 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H