Cyber Resilience

CVE-2020-3992

Memory Safety in Vmware Esxi 6.5 … 7.0.0

CISA KEVActive ExploitationEUVD ExploitedRansomware-linkedMemory Safety
Published
20 October 2020
Modified
12 August 2026
KEV Added
03 November 2021
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.83 99.6th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2020-3992 is a critical-severity Use After Free (CWE-416) vulnerability in Vmware Esxi. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 0.4% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2020-3992 is a use-after-free vulnerability (CWE-416) in the OpenSLP service as implemented in VMware ESXi. Affected releases include version 7.0 prior to ESXi_7.0.1-0.0.16850804, 6.7 prior to ESXi670-202010401-SG, and 6.5 prior to ESXi650-202010401-SG. The flaw carries a CVSS 3.1 base score of 9.8.

An unauthenticated attacker located on the management network and able to reach TCP/UDP port 427 can send crafted SLP packets that trigger the use-after-free condition, resulting in remote code execution with full control over the hypervisor.

VMware security advisory VMSA-2020-0023 and corresponding Zero Day Initiative reports ZDI-20-1377 and ZDI-20-1385 identify the issue and direct administrators to apply the listed ESXi updates that contain the corrected OpenSLP implementation. No public reports of in-the-wild exploitation appear in the provided references.

EU & UK References

Vulnerability Data

OpenSLP as used in VMware ESXi (7.0 before ESXi_7.0.1-0.0.16850804, 6.7 before ESXi670-202010401-SG, 6.5 before ESXi650-202010401-SG) has a use-after-free issue. A malicious actor residing in the management network who has access to port 427 on an ESXi machine may be able…

more

to trigger a use-after-free in the OpenSLP service resulting in remote code execution.

CWE(s)
CWE-416
KEV Date Added
03 November 2021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-22253Same product: Vmware Cloud Foundation
CVE-2023-20893Same product class: hypervisor / virtualization
CVE-2024-22252Same product: Vmware Esxi
CVE-2025-48543Shared CWE-416both on KEV
CVE-2024-1086Shared CWE-416both on KEV
CVE-2025-62221Shared CWE-416both on KEV
CVE-2010-0249Shared CWE-416both on KEV
CVE-2023-21674Shared CWE-416both on KEV
CVE-2023-28205Shared CWE-416both on KEV
CVE-2020-0674Shared CWE-416both on KEV

Affected Assets

vmware
cloud foundation
3.0 — 3.10.1.2 · 4.0 — 4.1.0.1
vmware
esxi
6.5, 6.7, 7.0.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V1.4.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly incorporate memory-safety tooling and reviews that prevent most use-after-free defects.

ID.RA-01 partial match
prevents

Vulnerability identification processes can discover use-after-free issues via scanning or analysis but do not prevent their introduction.

PR.PS-02 partial match
prevents

Routine patching removes known use-after-free instances after they have been introduced in released software.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect use-after-free bugs before release.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates memory-safety practices that reduce use-after-free defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-management rules that mitigate use-after-free.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles include memory-safety design choices that limit use-after-free exposure.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe avoidance of use-after-free patterns.

A.8.32 Change management partial match
prevents

Change-management processes help ensure memory-safety fixes are deployed consistently.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 8 (1 rule)
  • V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416
RHEL 9 (1 rule)
  • V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. prevents CWE-416

References