CVE-2025-2416: Akinsoft LimonDesk Auth Bypass Flaw

CVE-2025-2416 Overview

CVE-2025-2416 is an authentication bypass vulnerability in Akinsoft LimonDesk caused by improper restriction of excessive authentication attempts [CWE-307]. The flaw affects LimonDesk versions from s1.02.14 before v1.02.17. Attackers can submit unlimited authentication attempts against the application, enabling brute-force and credential-stuffing attacks against user accounts. The vulnerability is network-exploitable, requires no privileges, and needs no user interaction. Successful exploitation can lead to unauthorized account access within LimonDesk, a helpdesk and ticketing platform that typically stores customer support data and internal communications.

Critical Impact
Remote attackers can bypass authentication through unrestricted login attempts, gaining unauthorized access to LimonDesk accounts and the support data they contain.

Affected Products

Akinsoft LimonDesk s1.02.14 and later versions prior to v1.02.17
LimonDesk helpdesk and ticketing deployments exposed to untrusted networks
LimonDesk instances using only password-based authentication without external rate limiting

Discovery Timeline

2025-09-03 - CVE-2025-2416 published to NVD
2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-2416

Vulnerability Analysis

LimonDesk fails to enforce limits on the number of authentication attempts a client can submit against its login interface. Without lockouts, throttling, or CAPTCHAs, the application accepts repeated credential submissions from the same source. Attackers can iterate through password lists, leaked credential dumps, or common password dictionaries against valid usernames. The issue maps to [CWE-307]: Improper Restriction of Excessive Authentication Attempts.

Because LimonDesk often holds customer ticket data, internal notes, and agent communications, account takeover exposes sensitive support information. Attackers who obtain agent or administrator credentials can read tickets, impersonate staff, and pivot toward connected systems. The vulnerability is reachable over the network without prior authentication.

Root Cause

The root cause is the absence of authentication attempt controls in versions before v1.02.17. The application does not implement account lockout thresholds, progressive delays, IP-based rate limiting, or challenge mechanisms after failed logins. Each authentication request is processed independently, allowing automated tools to test credentials at high speed.

Attack Vector

An attacker sends repeated HTTP authentication requests to the LimonDesk login endpoint. Using automated tooling, the attacker submits username and password combinations from breach corpora or generated wordlists. Because no rate limit or lockout triggers, the attacker continues until a valid credential pair is found. Once authenticated, the attacker accesses the LimonDesk interface with the compromised user's privileges.

No verified proof-of-concept code is publicly available. See the USOM Security Advisory TR-25-0206 for vendor and national CERT details.

Detection Methods for CVE-2025-2416

Indicators of Compromise

High volumes of failed login requests against the LimonDesk authentication endpoint from a single source IP or distributed botnet
Successful authentication events immediately following long sequences of failures for the same account
LimonDesk session activity originating from geographies or networks inconsistent with the legitimate user
Anomalous off-hours logins to agent or administrator accounts

Detection Strategies

Parse LimonDesk application and web server logs for repeated POST requests to the login URL with varying credentials.
Correlate failed authentication counts per username and per source IP over short time windows to surface brute-force patterns.
Alert on first successful login from a new IP, user agent, or ASN for privileged LimonDesk accounts.

Monitoring Recommendations

Forward LimonDesk authentication logs and upstream reverse-proxy or WAF logs to a centralized SIEM for correlation.
Track baseline login failure rates per account and trigger alerts on statistically significant deviations.
Monitor for credential-stuffing signatures from threat intelligence feeds against the LimonDesk login surface.

How to Mitigate CVE-2025-2416

Immediate Actions Required

Upgrade Akinsoft LimonDesk to version v1.02.17 or later, which introduces controls on excessive authentication attempts.
Restrict network exposure of the LimonDesk login interface to trusted networks or VPN clients where feasible.
Reset passwords for all LimonDesk accounts, prioritizing administrators and agents, and enforce strong password policies.
Review authentication logs for the period before patching to identify potential prior account compromises.

Patch Information

Akinsoft addresses CVE-2025-2416 in LimonDesk v1.02.17. Apply the vendor update across all affected instances. Refer to the USOM Security Advisory TR-25-0206 for the official notification published by Türkiye's National Cyber Incident Response Center.

Workarounds

Place LimonDesk behind a web application firewall or reverse proxy that enforces per-IP and per-account login rate limiting.
Implement IP allowlisting on perimeter devices to restrict login access to known administrative and agent ranges.
Deploy fail2ban or equivalent log-driven blocking against repeated failed authentication entries in LimonDesk access logs.
Require multi-factor authentication at an upstream identity provider or reverse proxy when supported by the deployment.

bash

# Example nginx rate-limit configuration for the LimonDesk login endpoint
http {
    limit_req_zone $binary_remote_addr zone=limondesk_login:10m rate=5r/m;

    server {
        location /login {
            limit_req zone=limondesk_login burst=5 nodelay;
            proxy_pass http://limondesk_backend;
        }
    }
}