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

Quick assessment

Affected
FOSSBilling FOSSBilling
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

fossbilling是fossbilling团队开源的一种高效计费和客户管理方案。 fossbilling 0.5.4版本至0.8.0之前版本存在安全漏洞，该漏洞源于API角色处理中存在授权绕过，可能导致未经身份验证的攻击者访问特权 端点，无需有效凭据、会话或CSRF令牌即可调用管理员API方法。

AI Predicted 9.8 Difficulty: Trivial EPSS 0.51% · P41

Affected Version Matrix 1

VendorProduct Version RangeStatus
FOSSBilling FOSSBilling >= 0.5.4, < 0.8.0 affected
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I. Basic Information for CVE-2026-27604

Vulnerability Information
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Vulnerability Title
FOSSBilling: Improper API Role Validation (system) Enables Unauthenticated Access to Privileged Admin Functions
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
fossbilling 信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
fossbilling是fossbilling团队开源的一种高效计费和客户管理方案。 fossbilling 0.5.4版本至0.8.0之前版本存在安全漏洞，该漏洞源于API角色处理中存在授权绕过，可能导致未经身份验证的攻击者访问特权`/api/system/*`端点，无需有效凭据、会话或CSRF令牌即可调用管理员API方法。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
FOSSBilling FOSSBilling >= 0.5.4, < 0.8.0 -

II. Public POCs for CVE-2026-27604

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III. Intelligence Information for CVE-2026-27604

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Vendor Advisories for CVE-2026-27604 (2)

Same Patch Batch · FOSSBilling · 2026-06-23 · 4 CVEs total

CVE-2026-28496 FOSSBilling: Server-side template injection in Twig template rendering enables information
CVE-2026-23513 FOSSBilling: Broken Authorization in Client Transaction and Order Listings
CVE-2025-64105 FOSSBilling: IDOR Vulnerability in Support Ticket Creation

IV. Related Vulnerabilities

Same product: FOSSBilling
Same vendor: FOSSBilling
Same weakness: CWE-200

V. Comments for CVE-2026-27604

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