CVE-2026-112374
FOSSBilling before 0.8.9 Login CSRF via Staff Guest Login API
- State
- Published
- Severity
- 5.1 Medium
- Published
- Oct 30, 2026
- Updated
- Oct 30, 2026
- Reserved
- Oct 19, 2026
Description
FOSSBilling before 0.8.9 contains a Cross-Site Request Forgery vulnerability in the staff guest login endpoint (POST /api/guest/staff/login) that allows remote attackers to force authentication because checkGuestClientAuthentication() only allowlists client_login and client_create, leaving staff_login without CSRF or Origin validation. Attackers can host an auto-submitting HTML form with attacker-controlled credentials to silently log a victim's browser into the attacker's staff account.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.1 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 4.3 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N | VulnCheck |
Weaknesses
- CWE-352 Cross-Site Request Forgery (CSRF)
Affected Products
| Product | Versions |
|---|---|
FOSSBillingFOSSBilling |
|
References
- Vendor Advisoryvendor-advisorytechnical-description
- Vendor Patchpatchissue-tracking
- VulnCheck Advisory: FOSSBilling before 0.8.9 Login CSRF via Staff Guest Login APIthird-party-advisory
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