CVE-2020-17391
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 · uneditedThis vulnerability allows local attackers to disclose information on affected installations of Parallels Desktop 15.1.3-47255. 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 handler for HOST_IOCTL_INIT_HYPERVISOR in the prl_hypervisor kext. The issue results from the exposure of dangerous method or function to the unprivileged user. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of the kernel. Was ZDI-CAN-10518.
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 confidenceLocal privilege escalation vulnerability in Parallels Desktop 15.1.3-47255's prl_hypervisor kernel extension. The HOST_IOCTL_INIT_HYPERVISOR handler exposes a dangerous function to unprivileged users, allowing information disclosure. When chained with other vulnerabilities, this enables arbitrary kernel code execution.
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< 16.0.0CVSS 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
- None
- Availability
- None
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Check if Parallels Desktop is installedLook for /Applications/Parallels Desktop.app or check /Library/Application Support/Parallels/ for Parallels-related directoriesAffected if Parallels Desktop application directory exists on the system
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Identify installed Parallels Desktop versionRun: defaults read /Applications/Parallels\ Desktop.app/Contents/Info.plist CFBundleShortVersionString or check Parallels Desktop > About in the GUIAffected if Version is 15.1.3 through any version below 16.0.0 (versions prior to 16.0.0)
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Verify prl_hypervisor kernel extension is loadedRun: kextstat | grep -i prl_hypervisor or check System Preferences > Security & Privacy > General for loaded kernel extensions from ParallelsAffected if The prl_hypervisor.kext kernel extension is loaded in memory
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Confirm unprivileged user can access hypervisor IOCTL interfaceThis requires examining the /dev/prl_hypervisor device node permissions. Run: ls -la /dev/prl* 2>/dev/null to check device exists and its permissionsAffected if The prl_hypervisor device is accessible to non-root users (world-readable or group-readable without root ownership)
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Check for signs of exploitationReview system logs: log show --predicate 'subsystem == "com.parallels.kernel"' --last 24h for suspicious IOCTL calls or kernel panicsAffected if Kernel logs show unexpected HOST_IOCTL_INIT_HYPERVISOR calls from unprivileged processes or anomalous kernel behavior
User is affected if Parallels Desktop version is below 16.0.0 AND the prl_hypervisor kernel extension is loaded, allowing unprivileged access to the hypervisor IOCTL interface.
Generated from the published advisory. Verify against your own configuration.
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 data16.0.0
Apply the vendor patch from Parallels once available; prior to patch, limit system access to trusted users and monitor for exploitation attempts.
- Consultation2.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-17391 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-17391 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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