# CVE-2026-44253: Wazuh: Cluster Protocol Memory Exhaustion (DoS) via unbounded receive_str allocation and div_msg_box accumulation

> An authenticated cluster node can exhaust master memory via unbounded allocations, disrupting agent connectivity and alert processing in Wazuh deployments.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 25 Aug 2026
- **Also known as:** GHSA-h5r8-gvhv-cmp2

## What is CVE-2026-44253?

CVE-2026-44253 is a medium-severity denial of service vulnerability in Wazuh Wazuh, published on 19 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

Wazuh is a free and open source platform used for threat prevention, detection, and response. From 3.9.0 until 4.14.5 and 5.0.0-beta2, the Wazuh cluster protocol in framework/wazuh/core/cluster/common.py allows an authenticated cluster node to exhaust memory on the master. The receive_str() method accepts an attacker-controlled total for InBuffer without a maximum, so a new_str command can request a multi-gigabyte bytearray and repeated requests accumulate in in_str. The divided-message path also retains flag_divided fragments under unique counters in div_msg_box without a count, aggregate-size, or expiration limit. Exploitation can disrupt agent connectivity and alert processing across the monitored environment. This issue is fixed in versions 4.14.5 and 5.0.0-beta2.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value), CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-44253?

It affects 1 product.


Products: Wazuh Wazuh.

## How do I fix CVE-2026-44253?

No fix has been published for CVE-2026-44253 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-44253 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44253 exists.

## 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-2026-44253 and fix it if it is affected.

What it is: CVE-2026-44253 is a medium-severity denial of service vulnerability in Wazuh Wazuh, published on 19 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44253 exists.

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-2026-44253/ (Markdown: https://insights.sbomify.com/CVE-2026-44253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44253
- OSV: https://osv.dev/vulnerability/CVE-2026-44253

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-44253/
Summaries are generated and may contain mistakes; the official description above is the record.