CVE-2020-3950 — FUSION
HIGHCVE-2020-3950 is a high-severity (CVSS 7.8) Improper Privilege Management vulnerability in vmware fusion. It is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
VMware Fusion (11.x before 11.5.2), VMware Remote Console for Mac (11.x and prior before 11.0.1) and Horizon Client for Mac (5.x and prior before 5.4.0) contain a privilege escalation…
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2021-11-03. Federal agencies were required to remediate by 2022-05-03.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2020-3950.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-3950 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
VMware Fusion (11.x before 11.5.2), VMware Remote Console for Mac (11.x and prior before 11.0.1) and Horizon Client for Mac (5.x and prior before 5.4.0) contain a privilege escalation vulnerability due to improper use of setuid binaries. Successful exploitation of this issue may allow attackers with normal user privileges to escalate their privileges to root on the system where Fusion, VMRC or Horizon Client is installed.
Affected Products
fusionvmwarehorizon clientvmwareremote consolevmwareResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
VMware Fusion 11.5.2 - Privilege Escalation
by Rich Mirch · Mar 20, 2020
VMware Fusion - USB Arbitrator Setuid Privilege Escalation (Metasploit)
by Metasploit · Apr 16, 2020
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every vmware fusion deployment and check each version against the affected-products list above.
Fix
Apply the vmware fusion security patch or hotfix for CVE-2020-3950 on the affected version, following the vendor advisory for your exact build.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2020-3950 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.