# 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.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Jul 2026
- **Updated:** 29 Jul 2026
- **Also known as:** GHSA-8v62-p5rj-72x6

## 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 (Improper Restriction of Excessive Authentication Attempts)

## 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.

## Is CVE-2026-16347 being exploited?

There is no known exploitation of CVE-2026-16347 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-16347 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-16347 in the wild and no public exploit code.

Affected product: MikroTik Cloud Hosted Router. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-16347/ (Markdown: https://insights.sbomify.com/CVE-2026-16347/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-16347
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-16347
- OSV: https://osv.dev/vulnerability/CVE-2026-16347

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-16347/
Summaries are generated and may contain mistakes; the official description above is the record.