CVE-2026-112374

MEDIUM 4.3

FOSSBilling before 0.8.9 Login CSRF via Staff Guest Login API

CVSS Score

4.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-352
Vendor	fossbilling
Product	fossbilling
Published	Oct 30, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Affected Versions

FOSSBilling / FOSSBilling

0.1.0 < 0.8.9

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-h7w3-wp25-gf86 github.com: https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.9 vulncheck.com: https://www.vulncheck.com/advisories/fossbilling-before-login-csrf-via-staff-guest-login-api

Credits

Komiljon Ayubov