PT-2026-46229 · Fossbilling · Fossbilling

Published

2026-06-04

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Updated

2026-06-04

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CVE-2026-43926

CVSS v4.0

6.3

Medium

VectorAV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the password reset confirmation endpoint /client/reset-password-confirm/:hash is handled by a non-API controller and is not covered by FOSSBilling's rate limiter, which only applies to /api/* routes. This allows an attacker to probe the endpoint for valid reset tokens without any per-IP request limiting, attempt counting, or lockout mechanism. The endpoint acts as an oracle, returning a distinguishable response for valid versus invalid tokens (HTTP 200 vs HTTP 302 redirect). An attacker can submit unlimited token guesses to the password reset confirmation endpoint with no throttling applied. However, practical exploitability is significantly mitigated by the current token generation, which uses hash('sha256', random bytes(32)), providing 256 bits of entropy. Tokens also expire after 15 minutes and are deleted after successful use. The same architectural gap applies to other controller-served auth routes, including /staff/email/:hash (admin password reset confirmation) and /client/confirm-email/:hash (email confirmation). Version 0.8.0 fixes the issue. Some workarounds are available. Configure a reverse proxy (e.g., Nginx, Apache, Cloudflare) to apply per-IP rate limiting to the /client/reset-password-confirm/* and /staff/email/* paths and/or use a WAF rule to limit request rates to these endpoints.

Fix

Improper Restriction of Excessive Authentication Attempts

Weakness Enumeration

CWE-204CWE-307

Related Identifiers

CVE-2026-43926

Affected Products

Fossbilling