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CVE-2026-43926— FOSSBilling's password reset confirmation endpoint lacks rate limiting

Quick assessment

Affected
FOSSBilling FOSSBilling
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FOSSBilling是FOSSBilling开源的一个面向主机服务商和数字服务提供商的计费与客户管理平台。 FOSSBilling 0.8.0之前版本存在安全漏洞，该漏洞源于密码重置确认端点未受速率限制器保护，允许攻击者探测有效重置令牌，但实际利用受限于令牌生成的高熵值和短有效期。

AI Predicted 5.3 Difficulty: Theoretical EPSS 0.35% · P26

Possible ATT&CK Techniques 1 AI

T1110 · Brute Force

Affected Version Matrix 1

VendorProduct Version RangeStatus
FOSSBilling FOSSBilling < 0.8.0 affected
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I. Basic Information for CVE-2026-43926

Vulnerability Information
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Vulnerability Title
FOSSBilling's password reset confirmation endpoint lacks rate limiting
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
响应差异性信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
FOSSBilling 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FOSSBilling是FOSSBilling开源的一个面向主机服务商和数字服务提供商的计费与客户管理平台。 FOSSBilling 0.8.0之前版本存在安全漏洞，该漏洞源于密码重置确认端点未受速率限制器保护，允许攻击者探测有效重置令牌，但实际利用受限于令牌生成的高熵值和短有效期。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
FOSSBilling FOSSBilling < 0.8.0 -

II. Public POCs for CVE-2026-43926

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III. Intelligence Information for CVE-2026-43926

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Vendor Advisories for CVE-2026-43926 (1)

Vendor Pages for CVE-2026-43926 (1)

IV. Related Vulnerabilities

Same product: FOSSBilling
Same vendor: FOSSBilling
Same weakness: CWE-204

V. Comments for CVE-2026-43926

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