# CVE-2020-11881: Denial of service in n/a

> An unauthenticated remote attacker can crash the SMB server by sending modified setup-request packets, causing a denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9vhh-7m5h-q2cr

## What is CVE-2020-11881?

CVE-2020-11881 is a high-severity denial of service vulnerability in Mikrotik Routeros, published on 14 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An array index error in MikroTik RouterOS 6.41.3 through 6.46.5, and 7.x through 7.0 Beta5, allows an unauthenticated remote attacker to crash the SMB server via modified setup-request packets, aka SUP-12964.

Weakness: CWE-129 (Improper Validation of Array Index)

## Which versions are affected by CVE-2020-11881?

It affects 1 product.


Products: Mikrotik Routeros.

## How do I fix CVE-2020-11881?

No fix has been published for CVE-2020-11881 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-11881 being exploited?

There is no known exploitation of CVE-2020-11881 in the wild and no public exploit code.

Public exploit code:

- CVE-2020-11881: unauthenticated remote DoS for MikroTik SMB service. (github_poc): https://github.com/botlabsDev/CVE-2020-11881

## 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-2020-11881 and fix it if it is affected.

What it is: CVE-2020-11881 is a high-severity denial of service vulnerability in Mikrotik Routeros, published on 14 Sep 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-11881 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-2020-11881/ (Markdown: https://insights.sbomify.com/CVE-2020-11881/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-11881
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-11881
- OSV: https://osv.dev/vulnerability/CVE-2020-11881

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-11881/
Summaries are generated and may contain mistakes; the official description above is the record.