CVE-2026-43926

June 4, 2026, 3:41 p.m.

6.3
Medium

Description

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.

Product(s) Impacted

Vendor Product Versions
Fossbilling
  • Fossbilling
  • *, 0.8.0

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-204
Observable Response Discrepancy
The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a fossbilling fossbilling / / / / / / / /
a fossbilling fossbilling 0.8.0 / / / / / / /

References

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

Tags

[email protected]
CWE-204
2026-06-04
CVE-2026-43926

CVSS Score

6.3 / 10

CVSS Data - 4.0

  • Attack Vector: NETWORK
  • Attack Complexity: HIGH
  • Attack Requirements: PRESENT
  • Privileges Required: NONE
  • User Interaction: NONE
  • Scope:
  • Confidentiality Impact: LOW
  • Integrity Impact: NONE
  • Availability Impact: NONE
  • Exploit Maturity: NOT_DEFINED

    • CVSS:4.0/AV: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

    View Vector String

Timeline

Published: June 4, 2026, 2:16 p.m.
Last Modified: June 4, 2026, 3:41 p.m.

Status : Deferred

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

[email protected]

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.