known ransomware use

VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Vulnerability

Added to KEV
2021-11-03
Federal due date
2022-05-03
Vendor
VMware
Product
VMware ESXi and Horizon DaaS
EPSS
99.7th percentile (score 0.921, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Known
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2019-5544

CISA short description

VMware ESXi and Horizon Desktop as a Service (DaaS) OpenSLP contains a heap-based buffer overflow vulnerability that allows an attacker with network access to port 427 to overwrite the heap of the OpenSLP service to perform remote code execution.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.