CSRF in Fossbilling
CVE-2026-112374
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.
Vulnerability class: CSRF (Cross-Site Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-h7w3-wp25-gf86 (vendor-advisory, technical-description)
- github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.9 (issue-tracking, patch)
- www.vulncheck.com/advisories/fossbilling-before-login-csrf-via-staff-guest-logi… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-112374?
- CVE-2026-112374 is a medium-severity vulnerability in Fossbilling, classified under Cross-Site Request Forgery (CSRF). CVSS score: 4.3/10. Published 2026-10-30.
- How severe is CVE-2026-112374?
- Medium severity. CVSS v3 base score is 4.3 out of 10.