# CVE-2020-20211: Denial of service in n/a

> An authenticated remote attacker can cause a Denial of Service in Mikrotik RouterOS via a crafted packet triggering an assertion failure.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Jul 2021
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-jxc4-r8mv-r847

## What is CVE-2020-20211?

CVE-2020-20211 is a medium-severity denial of service vulnerability in Mikrotik Routeros, published on 7 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Mikrotik RouterOs 6.44.5 (long-term tree) suffers from an assertion failure vulnerability in the /nova/bin/console process. An authenticated remote attacker can cause a Denial of Service due to an assertion failure via a crafted packet.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2020-20211?

It affects 1 product.


Products: Mikrotik Routeros.

## How do I fix CVE-2020-20211?

No fix has been published for CVE-2020-20211 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-20211 being exploited?

There is no known exploitation of CVE-2020-20211 in the wild and no public exploit code.

## Other vulnerabilities in Mikrotik Routeros

- [CVE-2018-7445](https://insights.sbomify.com/CVE-2018-7445/): MikroTik RouterOS Stack-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2026-86060](https://insights.sbomify.com/CVE-2026-86060/): MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command (critical 9.2, exploited in the wild)
- [CVE-2018-14847](https://insights.sbomify.com/CVE-2018-14847/): MikroTik Router OS Directory Traversal (critical 9.1, exploited in the wild)
- [CVE-2026-67277](https://insights.sbomify.com/CVE-2026-67277/): MikroTik RouterOS Missing Authentication for Critical Function (high 8.8, exploited in the wild)
- [CVE-2026-67279](https://insights.sbomify.com/CVE-2026-67279/): Mikrotik RouterOS Improper Enforcement of Behavioral Workflow (medium 6.9, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-20211 and fix it if it is affected.

What it is: CVE-2020-20211 is a medium-severity denial of service vulnerability in Mikrotik Routeros, published on 7 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-20211 in the wild and no public exploit code.

Affected product: Mikrotik Routeros. 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-2020-20211/ (Markdown: https://insights.sbomify.com/CVE-2020-20211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-20211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-20211
- OSV: https://osv.dev/vulnerability/CVE-2020-20211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-20211/
Summaries are generated and may contain mistakes; the official description above is the record.