CVE-2026-53646

Status: DeferredHigh (7.7)—

FOSSBilling is a free, open-source billing and client management system. In versions 0.5.6 through 0.7.2, when a `ClientPasswordReset` record already exists for a client (from a previous unexpired reset request), subsequent calls to the `reset_password` guest API endpoint reuse the existing token instead of generating a new one. The 15-minute validity window is anchored to the first request's `created_at` timestamp, not the time of the most recent email.

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An attacker who obtained the original reset link remains able to use it even after the victim requests a new reset, because the original token is never invalidated or rotated. Version 0.8.0 patches 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` endpoint to minimize the window of opportunity, and/or manually clear expired `client_password_reset` records from the database after a client reports a suspected compromise.

CVSS

Version: 4.0
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/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
Base score: 7.7

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.31%
Percentile among all scored CVEs: 22
Score date: 10/3/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1203 Exploitation for Client Executionexecution85 %
Primary impactT1078.001 Default Accountsstealth · persistence · privilege escalation · initial access80 %
Secondary impactT1556.001 Domain Controller Authenticationdefense impairment · persistence · credential access75 %

UI:R + entrega de enlace malicioso requiere interacción del usuario (abrir enlace reset). Reutilización de token permite acceso no autorizado a cuenta (T1078.001) y modificación de credenciales (T1556.001).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Multi-factor Authentication User Training Privileged Process Integrity Privileged Account Management Password Policies Application Isolation and Sandboxing

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Fossbilling — Fossbilling^AI

CWEs

CWE-640

References

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-vp66-w6rc-x32p

Raw JSON (NVD)

Show

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  "id": "CVE-2026-53646",
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  "lastModified": "2026-07-07T15:16:48.033",
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