# CVE-2021-21296: Denial-of-service in Fleet

> A malicious actor with a valid node key can crash the Fleet server by sending a malformed request during a live query, causing denial of service.

- **Severity:** Low 2.7 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Feb 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-xwh8-9p3f-3x45

## What is CVE-2021-21296?

CVE-2021-21296 is a low-severity denial of service vulnerability in fleetdm fleet, published on 10 Feb 2021. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Fleet is an open source osquery manager. In Fleet before version 3.7.0 a malicious actor with a valid node key can send a badly formatted request that causes the Fleet server to exit, resulting in denial of service. This is possible only while a live query is currently ongoing. We believe the impact of this vulnerability to be low given the requirement that the actor has a valid node key. There is no information disclosure, privilege escalation, or code execution. The issue is fixed in Fleet 3.7.0.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2021-21296?

It affects 1 product.


Products: Fleetdm Fleet.

## How do I fix CVE-2021-21296?

No fix has been published for CVE-2021-21296 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21296 being exploited?

There is no known exploitation of CVE-2021-21296 in the wild and no public exploit code.

## Other vulnerabilities in fleetdm fleet

- [CVE-2020-26276](https://insights.sbomify.com/CVE-2020-26276/): SAML authentication vulnerability in Fleet (critical 10.0)
- [CVE-2026-103264](https://insights.sbomify.com/CVE-2026-103264/): Fleet before 4.87.0 Authentication Bypass via Device Identifiers (critical 9.3)
- [CVE-2026-23518](https://insights.sbomify.com/CVE-2026-23518/): Fleet has a JWT signature bypass vulnerability in Azure AD MDM enrollment (critical 9.3)
- [CVE-2026-26062](https://insights.sbomify.com/CVE-2026-26062/): Fleet server may terminate unexpectedly when handling certain gRPC requests (high 8.7)
- [CVE-2026-26061](https://insights.sbomify.com/CVE-2026-26061/): Fleet's unbounded request body read allows remote Denial of Service (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21296 and fix it if it is affected.

What it is: CVE-2021-21296 is a low-severity denial of service vulnerability in fleetdm fleet, published on 10 Feb 2021. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-21296 in the wild and no public exploit code.

Affected product: fleetdm fleet. 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-2021-21296/ (Markdown: https://insights.sbomify.com/CVE-2021-21296/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21296
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21296
- OSV: https://osv.dev/vulnerability/CVE-2021-21296

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21296/
Summaries are generated and may contain mistakes; the official description above is the record.