# CVE-2020-10101: Denial of service in n/a

> An attacker can crash the Zammad WebSocket server by sending non-JSON messages, 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:** 5 Mar 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-85q9-82qf-837m

## What is CVE-2020-10101?

CVE-2020-10101 is a high-severity denial of service vulnerability in Zammad Zammad, published on 5 Mar 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Zammad 3.0 through 3.2. The WebSocket server crashes when messages in non-JSON format are sent by an attacker. The message format is not properly checked and parsing errors not handled. This leads to a crash of the service process.

Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-10101?

It affects 1 product.


Products: Zammad Zammad.

## How do I fix CVE-2020-10101?

No fix has been published for CVE-2020-10101 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-10101 being exploited?

There is no known exploitation of CVE-2020-10101 in the wild and no public exploit code.

## Other vulnerabilities in Zammad Zammad

- [CVE-2026-102489](https://insights.sbomify.com/CVE-2026-102489/): Zammad GmbH Zammad Session Fixation (high 8.7, exploited in the wild)
- [CVE-2026-102490](https://insights.sbomify.com/CVE-2026-102490/): Zammad GmbH Zammad Improper Privilege Management (high 8.5, exploited in the wild)
- [CVE-2022-48021](https://insights.sbomify.com/CVE-2022-48021/): Code injection in n/a (critical 9.8)
- [CVE-2022-35490](https://insights.sbomify.com/CVE-2022-35490/): Security feature bypass in n/a (critical 9.8)
- [CVE-2021-42090](https://insights.sbomify.com/CVE-2021-42090/): Deserialization in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-10101 and fix it if it is affected.

What it is: CVE-2020-10101 is a high-severity denial of service vulnerability in Zammad Zammad, published on 5 Mar 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-2020-10101 in the wild and no public exploit code.

Affected product: Zammad Zammad. 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-2020-10101/ (Markdown: https://insights.sbomify.com/CVE-2020-10101/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-10101
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-10101
- OSV: https://osv.dev/vulnerability/CVE-2020-10101

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-10101/
Summaries are generated and may contain mistakes; the official description above is the record.