# CVE-2021-41821: Integer overflow in n/a

> An authenticated agent can cause a denial of service in Wazuh Manager via a crafted message triggering an integer underflow.

- **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:** 29 Sep 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-9p24-grw8-6g35

## What is CVE-2021-41821?

CVE-2021-41821 is a medium-severity vulnerability in Wazuh Wazuh, published on 29 Sep 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Wazuh Manager in Wazuh through 4.1.5 is affected by a remote Integer Underflow vulnerability that might lead to denial of service. A crafted message must be sent from an authenticated agent to the manager.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2021-41821?

It affects 1 product.


Products: Wazuh Wazuh.

## How do I fix CVE-2021-41821?

No fix has been published for CVE-2021-41821 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-41821 being exploited?

There is no known exploitation of CVE-2021-41821 in the wild and no public exploit code.

## Other vulnerabilities in Wazuh Wazuh

- [CVE-2025-24016](https://insights.sbomify.com/CVE-2025-24016/): Wazuh Server Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2024-32038](https://insights.sbomify.com/CVE-2024-32038/): Wazuh Analysis Engine Event Decoder Heap-based Buffer Overflow Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2021-44079](https://insights.sbomify.com/CVE-2021-44079/): Command injection in n/a (critical 9.8)
- [CVE-2024-1243](https://insights.sbomify.com/CVE-2024-1243/): Remote code execution and local privilege escalation in Wazuh Windows agent via NetNTLMv2 hash theft (critical 9.5)
- [CVE-2026-61800](https://insights.sbomify.com/CVE-2026-61800/): Wazuh cluster worker file sync allows arbitrary file write under /var/ossec (incomplete fix for CVE-2026-30893) (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41821 and fix it if it is affected.

What it is: CVE-2021-41821 is a medium-severity vulnerability in Wazuh Wazuh, published on 29 Sep 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-2021-41821 in the wild and no public exploit code.

Affected product: Wazuh Wazuh. 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-2021-41821/ (Markdown: https://insights.sbomify.com/CVE-2021-41821/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41821
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41821
- OSV: https://osv.dev/vulnerability/CVE-2021-41821

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41821/
Summaries are generated and may contain mistakes; the official description above is the record.