MikroTik RouterOS and Cloud Hosted Router

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Summary
Successful exploitation of this vulnerability could allow attackers to rapidly guess passwords and gain unauthorized system access. The following versions of MikroTik RouterOS and Cloud Hosted Router are affected:

RouterOS vers:all/* (CVE-2026-16347) Cloud Hosted Router vers:all/* (CVE-2026-16347)





CVSS
Vendor
Equipment
Vulnerabilities




v3 8.8
MikroTik
MikroTik RouterOS and Cloud Hosted Router Improper Restriction of Excessive Authentication Attempts




Background

Critical Infrastructure Sectors: Information Technology, Commercial Facilities Countries/Areas Deployed: Worldwide Company Headquarters Location: Latvia


Vulnerabilities

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CVE-2026-16347

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.
View CVE Details

Affected Products
MikroTik RouterOS and Cloud Hosted Router

Vendor:MikroTik
Product Version:MikroTik RouterOS: vers:all/*, MikroTik Cloud Hosted Router: vers:all/*
Product Status:known_affected


Remediations
MitigationNo fix is currently available from MikroTik. Until a fix is available, MikroTik recommends that users adopt the following mitigations: Use a strong VPN or other additional protection layer if the API is exposed to public networks.
MitigationConfigure the unsuccessful-attempt time range (0.1 to 0.5 seconds) in /ip service for all services, including the API, once available. MitigationConnect initially from a trusted network (LAN) port only, then configure the router per your security requirements. MitigationRestrict/limit access to management services from untrusted networks. MitigationApply firewall rules to control and restrict access to management services where possible.
MitigationUse long, randomly generated passwords rather than weak or default-simple ones, to keep the brute-force search space impractically large. MitigationKeep the default randomly generated device password, or replace it with an equally strong one, since minimum complexity isn't enforced by default. MitigationUsers are encouraged to reach out to MikroTik (https://mikrotik.com/support) for further support.https://mikrotik.com/support

Relevant CWE: CWE-307 Improper Restriction of Excessive Authentication Attempts

Metrics




CVSS Version
Base Score
Base Severity
Vector String




3.1
8.8
HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H


4.0
8.7
HIGH
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N








Acknowledgments

Andre Santos of UniÆo Geek reported this vulnerability to CISA


Legal Notice and Terms of Use
This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy).

Recommended Practices
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet. CISA reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures. CISA also provides a section for control systems security recommended practices
on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets. Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time. This vulnerability is not exploitable remotely.

Revision History

Initial Release Date: 2026-07-28




Date
Revision
Summary




2026-07-28
1
Initial Publication




Legal Notice and Terms of Use

https://www.cisa.gov/news-events/ics-advisories/icsa-26-209-05

2026-07-28 12:00 UTC

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