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CVE-2019-5544

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

  • Critical 9.8
  • Exploited: added to CISA KEV 3 Nov 2021
  • Used in ransomware campaigns

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.

Key facts

Published
6 Dec 2019
Last changed
21 Oct 2025
Assigned by
vmware
KEV added
3 Nov 2021
KEV fix due
3 May 2022
Used in ransomware
Yes, according to CISA
EPSS
98.129% likely to be exploited in the next 30 days, higher than 99.913% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: active; Automatable: yes; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 9.8CVSS 3.1, Criticalfrom CISA (ADP container)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

What to do

  • Apply updates per vendor instructions.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
n/aESXi and Horizon DaaS
  • ESXi 6.7 prior to patch release ESXi670-201912001, ESXi 6.5 prior to patch release ESXi650-201912001, ESXi 6.0 prior to patch release ESXi600-201912001 and Horizon DaaS 8.x prior to BZ-2467224-Disable (affected)

Timeline

  1. 6 Dec 2019 Published
  2. 3 Nov 2021 CVE-2019-5544 added to CISA KEV
  3. 3 Nov 2021 Added to the CISA KEV catalogue

Weakness

References