---
id: CVE-2017-17537
title: >-
  MikroTik RouterBOARD v6.39.2 and v6.40.5 allows an unauthenticated remote
  attacker to cause a denial of service by connecting to TCP port 53 and sending
  data that begins with many '\0' characters, possibly related to DNS.
summary: >-
  MikroTik RouterBOARD v6.39.2 and v6.40.5 allows an unauthenticated remote
  attacker to cause a denial of service by connecting to TCP port 53 and sending
  data that begins with many '\0' characters, possibly related to DNS.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-20
vendor: mikrotik
product: routerboard
affected:
  - routerboard = 6.39.2
  - routerboard = 6.40.5
published: '2017-12-13'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T21:17:04.613'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2017-17537'
references:
  - url: 'https://packetstorm.news/files/id/145382'
    label: cve@mitre.org
  - url: 'https://www.exploit-db.com/exploits/43200/'
    label: cve@mitre.org
  - url: 'https://www.exploit-db.com/exploits/43200/'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
epss: 0.0165
epssPercentile: 0.75077
ingestedAt: '2026-09-16T21:05:36.877Z'
---

## Overview

MikroTik RouterBOARD v6.39.2 and v6.40.5 allows an unauthenticated remote attacker to cause a denial of service by connecting to TCP port 53 and sending data that begins with many '\0' characters, possibly related to DNS.

## Affected

- `routerboard = 6.39.2`
- `routerboard = 6.40.5`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.