CVE-2026-27604: FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions
Affected: FOSSBilling · Exploitation: check available, not yet exploited
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 70% of scored CVEs
DescriptionCVE.org
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 products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- FOSSBilling · FOSSBilling>= 0.5.4, < 0.8.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Check available, not yet exploited. A public nuclei template can confirm it on a system you are authorised to test.
- CISA KEV
- Not listed
- Public check
- FOSSBilling 0.5.4-0.7.x - Unauthenticated System API Role Authorization Bypass · nuclei template in projectdiscovery/nuclei-templates
- Vendor
- FOSSBilling
- Published
- June 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-27604 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.