CVE-2026-27604
FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | Critical10.0 | 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 |
| NVDNVD · Deferred | 4.0 | Critical10.0 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 1.3% · top 30% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 10.0.
Weakness
- CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (opens in a new tab)All about CWE-200 and its CVEs
- CWE-306: Missing Authentication for Critical Function (opens in a new tab)All about CWE-306 and its CVEs
- CWE-862: Missing Authorization (opens in a new tab)All about CWE-862 and its CVEs
- CWE-863: Incorrect Authorization (opens in a new tab)All about CWE-863 and its CVEs
Affected products
- affected >= 0.5.4, < 0.8.0
References (3)
- https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-78x5-c8gw-8279 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-57mv-jm88-66jc (opens in a new tab)x_refsource_MISC
- https://www.vulncheck.com/blog/fossbilling-auth-bypass-ssti-rce (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-27604)Record last updated .