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Parallels DesktopApplication · Parallels

CVE-2021-31426

HIGH · 8.8 CVSS v3.1 Published 2021-04-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
90/100
Remediation priority · Urgent
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.1.2-49151. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the Parallels Tools component. The issue results from the lack of proper validation of user-supplied data, which can result in an integer overflow before allocating a buffer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel on the target guest system. Was ZDI-CAN-12791.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Integer overflow vulnerability in Parallels Tools component of Parallels Desktop 16.1.2-49151 allows local attackers with low-privileged code execution to escalate to kernel-level code execution on the guest system. The flaw results from lack of proper validation of user-supplied data before buffer allocation.

MitigationApply vendor patch from Parallels (update to patched version of Parallels Desktop). Until patched, restrict trusted users only on affected guest VMs to reduce attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Parallels DesktopApplication
Affected:= 16.1.2-49151

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Parallels Desktop version
    Open Parallels Desktop and navigate to the menu bar: Parallels Desktop > About Parallels Desktop. The version number will be displayed in the format like '16.1.2 (49151)'. Alternatively, right-click the Parallels Desktop icon in the Applications folder and select 'Get Info' to view version details.
    Affected if The installed version is exactly 16.1.2 build 49151.
  2. Confirm Parallels Tools installation status
    On the guest virtual machine, check if Parallels Tools is installed. In Windows guests, open Control Panel > Programs and Features and look for 'Parallels Tools' in the installed programs list. In macOS or Linux guests, check for the presence of Parallels kernel extensions or driver components.
    Affected if Parallels Tools is installed on the guest system. If Parallels Tools is not installed, this specific vulnerability cannot be exploited in that guest VM.
  3. Verify guest VM configuration
    Open Parallels Desktop, select the affected virtual machine, go to Virtual Machine > Configure > General, and confirm the operating system type and version running as the guest.
    Affected if A guest VM is running with Parallels Tools enabled. The vulnerability requires low-privileged code execution within the guest OS to escalate to kernel-level code on that same guest.

You are affected if your Parallels Desktop version is exactly 16.1.2 build 49151 AND you have Parallels Tools installed on at least one guest virtual machine.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor patch from Parallels (update to patched version of Parallels Desktop). Until patched, restrict trusted users only on affected guest VMs to reduce attack surface.

Fix this in Parallels Desktop Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-31426 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data