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.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.9 patch, issue-tracking
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 5.1 · fossbillingNVD modified 2026-10-30 12:10
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 3
- https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-h7w3-wp25-gf86 vendor-advisory, technical-description
- https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.9 patch, issue-tracking
- https://www.vulncheck.com/advisories/fossbilling-before-login-csrf-via-staff-guest-login-api third-party-advisory