Critical 10.0Published Jun 23, 2026

CVE-2026-27604FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions

Updated under an hour ago (Oct 26, 2026, 10:50 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 10.0 CRITICAL (v4.0, CNA)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
Weakness (CWE): CWE-200, CWE-306, CWE-862, CWE-863
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Jun 23, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

FOSSBilling FOSSBilling fossbilling:fossbilling (from the name)	from 0.5.4, < 0.8.0	CNA record

References

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-78x5-c8gw-8279x-refsource-confirm
https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-57mv-jm88-66jcx-refsource-misc
https://www.vulncheck.com/blog/fossbilling-auth-bypass-ssti-rcex-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.