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

Source: https://junglewise.ai/threats/cve-2019-5544-vmware-esxi-and-horizon-daas-openslp-heap-based-buffer-overflow  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2019-5544 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

A heap-based buffer overflow vulnerability in the OpenSLP service, as used in VMware ESXi and Horizon DaaS, allows a remote attacker with network access to port 427 to overwrite the heap. This can lead to remote code execution on the affected host.

Technologies: [Vmware Esxi](https://junglewise.ai/threats/technologies/esxi). Vendors: [VMware](https://junglewise.ai/threats/vendors/vmware).

## Quick answers

**Is CVE-2019-5544 exploited in the wild?** Yes. CVE-2019-5544 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2019-5544?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** VMware ESXi; VMware Horizon Desktop as a Service (DaaS) appliances; OpenSLP OpenSLP.

**Is there a fix for CVE-2019-5544?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2019-5544 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2019-5544?** Check whether you run VMware Horizon Daas or Vmware Esxi. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- VMware ESXi
- VMware Horizon Desktop as a Service (DaaS) appliances
- OpenSLP OpenSLP

## Timeline

- 2019-12-10: disclosed: Initial disclosure via VMware advisory VMSA-2019-0022 and mailing lists.
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog.
- 2021-11-03: disclosed: NVD publication date.