CVE-2019-5544: in the CISA KEV catalogue
VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Vulnerability. CISA added CVE-2019-5544 to the Known Exploited Vulnerabilities catalogue on 2021-11-03 with a default due date of 2022-05-03. Known ransomware campaign use: Known. Forensic triage flag: No.
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. (CISA description)
- Vendor / product
- VMware VMware ESXi and Horizon DaaS
- CWE
- CWE-787
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 98%, percentile 99 (scored 2026-11-03)
EPSS puts about 98 in 100 odds (98%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2019-5544 in the CISA KEV catalogue?
Yes. CISA added CVE-2019-5544 (VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2021-11-03. CISA's default due date for it is 2022-05-03.
Is CVE-2019-5544 used in ransomware attacks?
CISA marks known ransomware campaign use as Known for CVE-2019-5544.
What should I do about CVE-2019-5544?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2019-5544