MikroTik RouterOS and Cloud Hosted Router
All CISA Advisories, CISA, July 28, 2026
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
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.
Affected Products
MikroTik RouterOS and Cloud Hosted Router
MikroTik
MikroTik RouterOS: vers:all/*, MikroTik Cloud Hosted Router: vers:all/*
known_affected
Remediations
Mitigation
No 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.
Mitigation
Configure the unsuccessful-attempt time range (0.1 to 0.5 seconds) in /ip service for all services, including the API, once available.
Mitigation
Connect initially from a trusted network (LAN) port only, then configure the router per your security requirements.
Mitigation
Restrict/limit access to management services from untrusted networks.
Mitigation
Apply firewall rules to control and restrict access to management services where possible.
Mitigation
Use long, randomly generated passwords rather than weak or default-simple ones, to keep the brute-force search space impractically large.
Mitigation
Keep the default randomly generated device password, or replace it with an equally strong one, since minimum complexity isn’t enforced by default.
Mitigation
Users 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 União 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 |
