# CVE-2019-5544: VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow

> A heap overwrite vulnerability in OpenSLP allows remote attackers to execute arbitrary code on VMware ESXi and Horizon DaaS appliances.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Dec 2019
- **Updated:** 21 Oct 2025
- **Also known as:** AZL-36968, AZL-7321, GHSA-4734-5452-r5fh, MGASA-2020-0075, RHSA-2019:4240, RHSA-2020:0199, UBUNTU-CVE-2019-5544, USN-4919-1

## What is CVE-2019-5544?

CVE-2019-5544 is a critical memory corruption vulnerability in Fedoraproject Fedora, published on 6 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OpenSLP as used in ESXi and the Horizon DaaS appliances has a heap overwrite issue. VMware has evaluated the severity of this issue to be in the Critical severity range with a maximum CVSSv3 base score of 9.8.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2019-5544?

It affects 16 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openslp` | Red Hat:enterprise_linux:6::client | All versions | 1:2.0.0-4.el6_10 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 1:2.0.0-4.el6_10 |
| `openslp-devel` | Red Hat:enterprise_linux:6::client | All versions | 1:2.0.0-4.el6_10 |
| `openslp-server` | Red Hat:enterprise_linux:6::client | All versions | 1:2.0.0-4.el6_10 |
| `openslp` | Red Hat:enterprise_linux:6::computenode | All versions | 1:2.0.0-4.el6_10 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 1:2.0.0-4.el6_10 |
| `openslp-devel` | Red Hat:enterprise_linux:6::computenode | All versions | 1:2.0.0-4.el6_10 |
| `openslp-server` | Red Hat:enterprise_linux:6::computenode | All versions | 1:2.0.0-4.el6_10 |
| `openslp` | Red Hat:enterprise_linux:6::server | All versions | 1:2.0.0-4.el6_10 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:6::server | All versions | 1:2.0.0-4.el6_10 |
| `openslp-devel` | Red Hat:enterprise_linux:6::server | All versions | 1:2.0.0-4.el6_10 |
| `openslp-server` | Red Hat:enterprise_linux:6::server | All versions | 1:2.0.0-4.el6_10 |
| `openslp` | Red Hat:enterprise_linux:6::workstation | All versions | 1:2.0.0-4.el6_10 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:6::workstation | All versions | 1:2.0.0-4.el6_10 |
| `openslp-devel` | Red Hat:enterprise_linux:6::workstation | All versions | 1:2.0.0-4.el6_10 |
| `openslp-server` | Red Hat:enterprise_linux:6::workstation | All versions | 1:2.0.0-4.el6_10 |
| `openslp` | Red Hat:enterprise_linux:7::client | All versions | 1:2.0.0-8.el7_7 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:7::client | All versions | 1:2.0.0-8.el7_7 |
| `openslp-devel` | Red Hat:enterprise_linux:7::client | All versions | 1:2.0.0-8.el7_7 |
| `openslp-server` | Red Hat:enterprise_linux:7::client | All versions | 1:2.0.0-8.el7_7 |
| `openslp` | Red Hat:enterprise_linux:7::computenode | All versions | 1:2.0.0-8.el7_7 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:7::computenode | All versions | 1:2.0.0-8.el7_7 |
| `openslp-devel` | Red Hat:enterprise_linux:7::computenode | All versions | 1:2.0.0-8.el7_7 |
| `openslp-server` | Red Hat:enterprise_linux:7::computenode | All versions | 1:2.0.0-8.el7_7 |
| `openslp` | Red Hat:enterprise_linux:7::server | All versions | 1:2.0.0-8.el7_7 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 1:2.0.0-8.el7_7 |
| `openslp-devel` | Red Hat:enterprise_linux:7::server | All versions | 1:2.0.0-8.el7_7 |
| `openslp-server` | Red Hat:enterprise_linux:7::server | All versions | 1:2.0.0-8.el7_7 |
| `openslp` | Red Hat:enterprise_linux:7::workstation | All versions | 1:2.0.0-8.el7_7 |
| `openslp-debuginfo` | Red Hat:enterprise_linux:7::workstation | All versions | 1:2.0.0-8.el7_7 |
| `openslp-devel` | Red Hat:enterprise_linux:7::workstation | All versions | 1:2.0.0-8.el7_7 |
| `openslp-server` | Red Hat:enterprise_linux:7::workstation | All versions | 1:2.0.0-8.el7_7 |

Products: Fedoraproject Fedora, Openslp Openslp, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux for Ibm Z Systems, Redhat Enterprise Linux for Ibm Z Systems Eus, Redhat Enterprise Linux for Power Big Endian, Redhat Enterprise Linux for Power Big Endian Eus, Redhat Enterprise Linux for Power Little Endian, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Enterprise Linux Server, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server Eus, Redhat Enterprise Linux Server Tus, Redhat Enterprise Linux Workstation, Vmware Esxi, Vmware Horizon Daas.

## How do I fix CVE-2019-5544?

Apply the vendor's patch. US federal agencies must fix it by 3 May 2022.

## Is CVE-2019-5544 being exploited?

Yes. Attackers have exploited CVE-2019-5544 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Public exploit code:

- CVE-2020-3992 & CVE-2019-5544 (github_poc): https://github.com/dgh05t/VMware_ESXI_OpenSLP_PoCs
- Python / scapy module implementing SRVLOC/SLP protocol and scans for enabled OpenSLP services. (github_poc): https://github.com/HynekPetrak/CVE-2019-5544_CVE-2020-3992
- VMware ESXi SLP - Heap Overflow DoS (nuclei)

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- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
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- [CVE-2022-3075](https://insights.sbomify.com/CVE-2022-3075/): Google Chromium Mojo Insufficient Data Validation (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-5544 and fix it if it is affected.

What it is: CVE-2019-5544 is a critical memory corruption vulnerability in Fedoraproject Fedora, published on 6 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2019-5544 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Affected product: Fedoraproject Fedora. 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-2019-5544/ (Markdown: https://insights.sbomify.com/CVE-2019-5544/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-5544
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-5544
- OSV: https://osv.dev/vulnerability/CVE-2019-5544

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-5544/
Summaries are generated and may contain mistakes; the official description above is the record.