CVE-2026-43926

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.

CVSS

No CVSS.

References

Link	Resource
https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0
https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-cqqm-p3x5-9fqg

Configurations

No configuration.

History

04 Jun 2026, 14:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-06-04 14:16

Updated : 2026-06-04 15:41

NVD link : CVE-2026-43926

Mitre link : CVE-2026-43926

CVE.ORG link : CVE-2026-43926

JSON object : View

Products Affected

No product.

CWE

CWE-204

Observable Response Discrepancy

CWE-307

Improper Restriction of Excessive Authentication Attempts

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