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Parallels DesktopApplication · Parallels

CVE-2023-27327

HIGH · 7.5 CVSS v3.0 Published 2024-05-03
Fix available
A fix is available. Upgrade to 18.1.1_ or later.
See remediation →
77/100
Remediation priority · High
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
Parallels Desktop Toolgate Time-Of-Check Time-Of-Use Local Privilege Escalation Vulnerability. This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop. An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the Toolgate component. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the current user on the host system. Was ZDI-CAN-18964.

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

This is a Time-Of-Check Time-Of-Use (TOCTOU) race condition vulnerability in the Toolgate component of Parallels Desktop hypervisor. The flaw stems from improper locking during object operations, allowing an attacker who already has high-privileged code execution on a guest VM to race the check-use window and execute arbitrary code with the current user's privileges on the host system.

MitigationApply the vendor security patch for Parallels Desktop when available; in the meantime, restrict execution of untrusted code within guest VMs and limit VM access to trusted users 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:< 18.1.1_\(53328\)

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
High
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:H/PR:H/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. Verify Parallels Desktop is installed
    On macOS host, check for Parallels Desktop application: ls /Applications | grep -i parallels or check via System Settings > Privacy & Security > Scroll down for Parallels entries
    Affected if Parallels Desktop application exists on the system
  2. Determine installed Parallels Desktop version
    Open Parallels Desktop, go to Parallels Menu > About Parallels, or run: defaults read /Applications/Parallels\ Desktop.app/Contents/Info.plist CFBundleVersion. Compare the version number to 18.1.1 (build 53328)
    Affected if Version is lower than 18.1.1 or build number is lower than 53328
  3. Identify if Toolgate feature is in use
    Check VM configuration files (.pvm) in ~/Parallels/ for any Toolgate-related settings, or inspect: prlctl list -a -o name,status and check for guest tools mounted/active
    Affected if Guest VMs have Parallels Tools installed and Toolgate component is active between guest and host
  4. Assess VM execution environment
    Review which users have access to create/run VMs and whether untrusted code could be executed within guest VMs by listing VM files and checking permissions
    Affected if Untrusted users or code have access to guest VMs with Parallels Tools installed

A host is affected if Parallels Desktop version is below 18.1.1 (build 53328) AND the Toolgate component is accessible through guest VMs that could be populated with attacker-controlled high-privileged 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
Upgrade available Upgrade to 18.1.1_ or later
Fixed in 18.1.1_
Interim mitigation

Apply the vendor security patch for Parallels Desktop when available; in the meantime, restrict execution of untrusted code within guest VMs and limit VM access to trusted users to reduce attack surface.

Recommended fix High confidence

Parallels Desktop 18.1.1 (build 53328) or later

  1. Back up all virtual machines and important data before updating
  2. Download Parallels Desktop version 18.1.1 (build 53328) or later from the official Parallels website (parallels.com)
  3. Install the updated version following the installation wizard prompts
  4. Restart your computer if prompted after installation
  5. Verify the installed version is 18.1.1 (build 53328) or higher via Parallels Desktop > About
Caveat Review Parallels release notes for any feature changes before upgrading

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

Fix this in Parallels Desktop Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,390
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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-2023-27327 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