Threats / VMware / CVE-2019-5544
CVE-2019-5544
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
VMware ESXi and Horizon DaaS vulnerability
VMware ESXi and Horizon DaaS OpenSLP service contains a heap-based buffer overflow on port 427 enabling unauthenticated remote code execution.
Verdict
Today item, not a backlog item.
A network-accessible heap overflow in OpenSLP allows attackers to execute arbitrary code on virtualization infrastructure without authentication, creating direct paths to hypervisor compromise and lateral movement.
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
11 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.96823 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: VMware, VMware ESXi and Horizon DaaS. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious OpenSLP packet and send it to port 427 on an exposed ESXi or Horizon DaaS host.
Business
Attacker gains code execution on core virtualization infrastructure without credentials.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I exploit the heap overflow to overwrite memory and execute my payload with ESXi service privileges.
Business
Attacker achieves persistent control of the hypervisor layer, compromising all guest virtual machines.
3
Lateral reach — past segmentation narrative 3
Attacker
I use hypervisor access to move laterally across the datacenter or deploy ransomware to encrypted datastores.
Business
Enterprise loses availability of entire virtualized infrastructure and data; recovery requires clean restoration.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05