CVE-2026-16347
View CSAF 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 Expand All + 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 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 conf
CSIRTS triage
- What
- A vulnerability allows attackers to rapidly guess passwords and gain unauthorized system access due to improper authentication handling.
- Who is affected
- Deployments of MikroTik RouterOS and Cloud Hosted Router worldwide.
- Urgency
- Remediation is critical as the vulnerability has a high severity (CVSS 8.8) and could lead to unauthorized access.
- Action
- Implement rate-limiting and account lockout measures, and update to the latest versions.
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Exploitation outlook
- Low exploitation risk0.23% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 14% of all EPSS-scored CVEs.
Advisory coverage (2)
- highCVE-2026-16347: MikroTik RouterOS contains a weakness in its API authentication handling that lacks effective …nvd · 2026-07-28
- criticalMikroTik RouterOS and Cloud Hosted Routercisa · 2026-07-28
External references
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