CVE-2025-42615 | Improper Restriction of Excessive Authentication Attempts vulnerability in CIRCL Vulnerability-Lookup

In affected versions, vulnerability-lookup did not track or limit failed One-Time Password (OTP) attempts during Two-Factor Authentication (2FA) verification. An attacker who already knew or guessed a valid username and password could submit an arbitrary number of OTP codes without causing the account to be locked or generating any specific alert for administrators. This lack of rate-limiting and lockout on OTP failures significantly lowers the cost of online brute-force attacks against 2FA codes and increases the risk of successful account takeover, especially if OTP entropy is reduced (e.g. short numeric codes, user reuse, or predictable tokens). Additionally, administrators had no direct visibility into accounts experiencing repeated 2FA failures, making targeted attacks harder to detect and investigate. The patch introduces a persistent failed_otp_attempts counter on user accounts, locks the user after 5 invalid OTP submissions, resets the counter on successful verification, and surfaces failed 2FA attempts in the admin user list. This enforces an account lockout policy for OTP brute-force attempts and improves monitoring capabilities for suspicious 2FA activity.This issue affects Vulnerability-Lookup: before 2.18.0.