CVE-2021-31420

Local privilege escalation via Toolgate overflow

Published Apr 29, 2021 · Updated Aug 3, 2024

A stack-based buffer overflow in Parallels Desktop 16.1.0-48950 allows local attackers to escalate privileges via guest-executed code. Toolgate copies length-unvalidated user data into a fixed-size stack buffer, enabling arbitrary code execution in the hypervisor context. Exploitation requires low-privileged code execution inside a guest; the resulting access crosses into the hypervisor and can affect host confidentiality, integrity, and availability.

CVSS severity8.8
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A stack-based buffer overflow in Parallels Desktop 16.1.0-48950 allows local attackers to escalate privileges via guest-executed code. Toolgate copies length-unvalidated user data into a fixed-size stack buffer, enabling arbitrary code execution in the hypervisor context. Exploitation requires low-privileged code execution inside a guest; the resulting access crosses into the hypervisor and can affect host confidentiality, integrity, and availability.

The record

CVE
CVE-2021-31420
Published
Apr 29, 2021
Updated
Aug 3, 2024
Vendor
Parallels
Product
Parallels Desktop
Classifications
CWE-121, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=16.1.0-48950

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Parallels · Parallels Desktopversion=16.1.0-48950

Published CVSS scores

8.8Zero Day InitiativeCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
8.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
4.6NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

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.

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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-121Stack-based Buffer Overflow
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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