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Parallels DesktopApplication · Parallels

CVE-2021-31425

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 guest 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-12790.

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

Local privilege escalation vulnerability in Parallels Desktop's Parallels Tools component. The flaw stems from insufficient validation of user-supplied data that can trigger an integer overflow before buffer allocation, allowing an attacker with initial low-privileged code execution to escalate to kernel-level privileges within the guest system.

MitigationApply the vendor-supplied patch or update Parallels Desktop to a patched version. Until patched, restrict execution of untrusted code within the guest virtual machine to reduce the 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. Confirm Parallels Desktop is installed
    On the macOS host, check for Parallels Desktop application in /Applications or via System Preferences > Security & Privacy > General to see if it was installed from the App Store. Alternatively, run 'ls /Applications | grep -i parallels' in terminal.
    Affected if Parallels Desktop is not installed on the system.
  2. Identify installed Parallels Desktop version
    Open Parallels Desktop, go to Help > About Parallels Desktop, or run 'prlctl --version' on the macOS host to retrieve the exact version and build number.
    Affected if The installed version is exactly 16.1.2 build 49151.
  3. Verify Parallels Tools is installed in the guest VM
    Within the guest operating system (the virtual machine), check if Parallels Tools are installed. On Windows guest: look for Parallels Tools in Add/Remove Programs or check C:\Program Files\Parallels\Parallels Tools. On Linux guest: check /usr/lib/parallels-tools or run 'lsmod | grep prl'
    Affected if Parallels Tools are installed and running in the guest virtual machine.
  4. Assess guest VM execution environment
    Determine whether untrusted or low-privileged code can execute within the guest virtual machine. Review installed software, user permissions, and application execution policies.
    Affected if Untrusted or low-privileged users can execute code within the guest VM.

A system is affected if Parallels Desktop version 16.1.2-49151 is installed with Parallels Tools enabled in the guest VM and the guest permits execution of untrusted code.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied patch or update Parallels Desktop to a patched version. Until patched, restrict execution of untrusted code within the guest virtual machine to reduce the attack surface.

Recommended fix Moderate confidence

Parallels Desktop version later than 16.1.2-49151 (verify fixed release on kb.parallels.com)

  1. 1. Verify the current Parallels Desktop version by going to Parallels Desktop menu > About Parallels Desktop
  2. 2. Check Parallels support portal (kb.parallels.com) or the official security advisory for the fixed version addressing CVE-2021-31425
  3. 3. If a newer version is available, download and install the update
  4. 4. After upgrading, ensure Parallels Tools are updated to the latest version within the guest虚拟机
  5. 5. Restart the virtual machine to apply all updates
Caveat Review release notes for any compatibility changes or migration requirements before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Parallels Desktop Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,120
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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-2021-31425 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