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Vulnerability Analysis
FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions

CVE-2026-27604

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.

No Active Exploit Signals
CVSS Base Score
10.0
CRITICAL
Exploitability:-
Impact Score:-
Temporal Score:-
EPSS:0.41%

Threat Intelligence Signals

CISA KEV
No
KEV Date Added
Ransomware Use
KEV Due Date
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.408%
EPSS Percentile
32.4th pct
GHSA ID
GitHub Severity
SSVC Exploitation
SSVC Automatable
Vulnerability Class

Identity & Timeline

Status-
Assigning Authority-
CVSS Version / Source-
Reserved-
Published-
Patch Date (date_public)-
Exploit DB Date-
First GitHub PoC Date-
Last Updated-
Time to Patch (Days to fix)-
Exploit Release Gap-
PoC Release Gap-
Exploit DB ReferencesNone identified

Affected Products & Versions

Vendor Product Affected Versions
No affected products specified.

References

No reference links found.

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