CVE-2020-3957

Local root escalation via service opener race

Published May 29, 2020 · Updated Aug 4, 2024

Local privilege escalation in VMware Fusion 11.x before 11.5.5 allows local users to gain root privileges via a service opener race. The service opener performs a time-of-check/time-of-use operation that can be won by a normal macOS user. Successful exploitation requires local account access and results in root-level control on systems running the affected Fusion, VMRC for Mac, or Horizon Client for Mac builds.

CVSS severity7.3
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Local privilege escalation in VMware Fusion 11.x before 11.5.5 allows local users to gain root privileges via a service opener race. The service opener performs a time-of-check/time-of-use operation that can be won by a normal macOS user. Successful exploitation requires local account access and results in root-level control on systems running the affected Fusion, VMRC for Mac, or Horizon Client for Mac builds.

The record

CVE
CVE-2020-3957
Published
May 29, 2020
Updated
Aug 4, 2024
Vendor
VMware
Product
VMware Fusion
Classifications
CWE-367, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 29, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=11.x before 11.5.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

VMware · VMware Fusionversion=11.x before 11.5.5
VMware · VMware Horizon Client for Macversion=5.x and prior
VMware · VMware Remote Consoleversion=V11.x and prior

Published CVSS scores

7.3VMwareCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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