CVE-2026-16347 Improper restriction of excessive authentication attempts in MikroTik RouterOS and Cloud Hosted Router
Attackers can bypass authentication rate limits to brute-force credentials and gain unauthorized administrative access to MikroTik network devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-16347?
CVE-2026-16347 is a high-severity authentication bypass vulnerability in MikroTik Cloud Hosted Router, published on 28 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-307
Which versions are affected by CVE-2026-16347?
How do I fix CVE-2026-16347?
No fix has been published for CVE-2026-16347 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-16347 being exploited?
There is no known exploitation of CVE-2026-16347 in the wild and no public exploit code.
Sources
Also known as GHSA-8v62-p5rj-72x6.