CVE-2026-16347 in MikroTik
Summary
by MITRE • 07/28/2026
MikroTik RouterOS contains a weakness in its API authentication handling that lacks effective safeguards against excessive login attempts. The system does not enforce meaningful rate-limiting, account lockout, or source-based restrictions, allowing repeated authentication failures to proceed without defensive response. In some versions, a fixed per-connection delay is present, but it can be bypassed through concurrent sessions, resulting in continued high-volume attempts. This deficiency increases the risk that an attacker could eventually obtain valid credentials and gain unauthorized access to administrative services.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerability identified in MikroTik RouterOS represents a critical weakness in authentication security mechanisms that directly impacts the integrity of network administrative access controls. This flaw resides within the API authentication handling subsystem where the system fails to implement adequate protective measures against brute force and credential stuffing attacks. The absence of effective rate-limiting capabilities means that malicious actors can continuously attempt authentication without facing meaningful delays or account lockout mechanisms that would typically deter such attacks. The vulnerability aligns with CWE-307, which addresses improper restriction of repeated authentication attempts, making it a direct descendant of well-established authentication weakness patterns that have been documented in cybersecurity literature for decades.
The technical implementation of this vulnerability manifests through the lack of comprehensive session management and authentication throttling controls within the RouterOS API framework. While some versions may include a fixed per-connection delay mechanism, this protection proves insufficient when attackers employ concurrent connection strategies to bypass individual session limitations. The system's inability to track failed authentication attempts across multiple connections allows for rapid credential testing without meaningful defensive responses. This architectural oversight creates an environment where automated attack tools can systematically test large credential sets against the administrative API endpoints, exploiting the absence of source-based restrictions that would normally limit access attempts from specific IP addresses or connection sources.
The operational impact of this vulnerability extends beyond simple unauthorized access scenarios to encompass potential complete network compromise and lateral movement capabilities. An attacker who successfully exploits this weakness gains administrative privileges over the affected MikroTik device, enabling them to modify network configurations, redirect traffic, disable security features, and potentially use the compromised device as a pivot point for attacking other systems within the network perimeter. This risk is particularly concerning given that MikroTik devices are commonly deployed in enterprise and residential networks where they serve as primary routing and firewall functions. The vulnerability creates opportunities for attackers to leverage the compromised administrative access for data exfiltration, establishing persistent backdoors, or conducting advanced persistent threat operations as outlined in the attack tactics described in the MITRE ATT&CK framework under the credential access and privilege escalation domains.
Organizations should implement immediate mitigations including network-level restrictions on API access from unauthorized sources, deployment of intrusion detection systems to monitor for unusual authentication patterns, and configuration of external firewalls to limit access to administrative ports. The implementation of strong account lockout policies combined with source-based restrictions would significantly reduce the attack surface for this vulnerability. Additionally, regular security audits should verify that authentication mechanisms are properly configured and that default credentials have been changed across all affected devices. Organizations should also consider implementing multi-factor authentication where possible and establish monitoring procedures to detect anomalous login patterns that could indicate active exploitation attempts. The remediation approach should align with industry best practices for authentication security as outlined in standards such as NIST SP 800-63B, which emphasizes the importance of robust authentication mechanisms and protection against credential guessing attacks.