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 target the authentication mechanism over the network without prior credentials or user interaction. Successful exploitation leads to authentication bypass, exposing helpdesk data and administrative functions to unauthorized parties. The vulnerability was published to the National Vulnerability Database (NVD) on September 3, 2025, and was last modified on April 15, 2026.

Critical Impact

Network-accessible authentication bypass allowing unauthorized access to LimonDesk accounts through brute-force or credential-stuffing attacks against the login endpoint.

Affected Products

• Akinsoft LimonDesk s1.02.14
• Akinsoft LimonDesk versions after s1.02.14 and before v1.02.17
• Fixed in Akinsoft LimonDesk v1.02.17

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 a limit on the number of failed authentication attempts against its login interface. This weakness, classified as [CWE-307] Improper Restriction of Excessive Authentication Attempts, allows attackers to submit unlimited credential guesses without triggering account lockout, rate limiting, or progressive delay mechanisms. The authentication endpoint is reachable over the network, requires no prior privileges, and demands no user interaction, making automated abuse straightforward.

The Exploit Prediction Scoring System (EPSS) reports a probability of 0.072% with a percentile of 21.748 as of May 11, 2026. No public proof-of-concept exploit code is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Root Cause

The root cause is the absence of server-side controls that restrict repeated failed authentication attempts. Effective controls typically include account lockout thresholds, IP-based rate limiting, exponential backoff, and CAPTCHA challenges after a defined number of failures. LimonDesk versions prior to v1.02.17 ship without these enforcement layers on the login flow.

Attack Vector

An unauthenticated remote attacker can launch automated brute-force or credential-stuffing campaigns against the LimonDesk authentication endpoint. Using common tooling, the attacker iterates through password lists or breached credential pairs until valid credentials are discovered. Once authenticated, the attacker gains access to ticketing data, customer records, and any administrative capabilities tied to the compromised account.

No verified exploitation code is available. See the USOM Security Notification TR-25-0206 for advisory details.

Detection Methods for CVE-2025-2416

Indicators of Compromise

• High volume of failed login events originating from a single IP address or distributed across a botnet targeting the LimonDesk login endpoint.
• Successful authentication immediately following a burst of failed attempts for the same user account.
• Logins from geolocations or ASNs that do not match the historical access pattern of the user.
• New sessions established outside normal business hours for administrative accounts.

Detection Strategies

• Aggregate authentication logs from LimonDesk and correlate failed-to-successful login ratios per source IP and per username.
• Alert on more than a defined threshold of failed authentications within a short rolling window, for example 10 failures in 60 seconds.
• Use web application firewall (WAF) telemetry to identify repeated POST requests against the LimonDesk login URL.
• Baseline normal login behavior per user and flag deviations in source IP, user agent, or session timing.

Monitoring Recommendations

• Forward LimonDesk application and web server access logs to a centralized SIEM for correlation and long-term retention.
• Monitor reverse proxy and load balancer logs for HTTP 401 and 403 response spikes targeting authentication routes.
• Track newly created or modified user accounts and privilege changes within LimonDesk for post-compromise activity.

How to Mitigate CVE-2025-2416

Immediate Actions Required

• Upgrade Akinsoft LimonDesk to version v1.02.17 or later, which addresses the missing authentication attempt restrictions.
• Reset passwords for all LimonDesk accounts and require strong, unique credentials, especially for administrative users.
• Review authentication logs since the deployment of affected versions for evidence of brute-force activity or unexpected successful logins.
• Restrict network exposure of the LimonDesk login interface to trusted networks or VPN where feasible.

Patch Information

Akinsoft has resolved CVE-2025-2416 in LimonDesk v1.02.17. All deployments running s1.02.14 through versions prior to v1.02.17 should be upgraded. Refer to the USOM Security Notification TR-25-0206 for the official advisory.

Workarounds

• Place LimonDesk behind a reverse proxy or WAF configured to rate-limit requests to the authentication endpoint by source IP.
• Enforce IP allowlisting for administrative access until the patched version is deployed.
• Implement multi-factor authentication at an upstream identity provider if LimonDesk is integrated with SSO.
• Disable or remove inactive and default accounts to reduce the brute-force attack surface.

# Example NGINX rate-limiting 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;
        }
    }
}