High severity · published Jul 28, 2026
CVE-2026-16347
Improper restriction of excessive authentication attempts in MikroTik RouterOS and Cloud Hosted Router
8.8
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 33% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CH
Cloud Hosted Router · MikroTik
All versions · source: vendor
RO
RouterOS · MikroTik
All versions · source: vendor
In the news
VulnerabilityHigh
MikroTik RouterOS and Cloud Hosted Router
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 Vendo...
Jul 28, 2026·CISA Advisories