CVE-2021-27244
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 sensitive information on affected installations of Parallels Desktop 16.0.1-48919. 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 Toolgate component. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated buffer. An attacker can leverage this in conjunction with other vulnerabilities to escalate privileges and execute arbitrary code in the context of the hypervisor. Was ZDI-CAN-11925.
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 confidenceCVE-2021-27244 is an information disclosure vulnerability in Parallels Desktop's Toolgate component. The flaw results from insufficient validation of user-supplied data, allowing a read past the end of an allocated buffer. Exploitation requires low-privileged code execution on the guest system and can be chained with other vulnerabilities to escalate privileges and execute arbitrary code in the hypervisor context.
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= 16.0.1CVSS 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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Identify installed Parallels Desktop versionOpen Parallels Desktop and navigate to the Help menu, or check the application's 'About' window to display the full version number including build identifierAffected if The version displayed is exactly 16.0.1 (no build suffix or later build shown)
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Confirm the specific build of version 16.0.1Locate the complete build number in the application's version details (typically shown as version-build format, for example 16.0.1-48919)Affected if The build number is 48919 or earlier (meaning it matches the affected 16.0.1 release)
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Determine if Toolgate component is activeCheck Parallels Desktop configuration settings or system integration modules for the Toolgate feature status. This component handles communication between guest and host systems.Affected if Toolgate is enabled and running in the current configuration
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Assess guest virtual machine accessReview who has access to the guest operating system and what privileges they possess. The vulnerability requires low-privileged code execution within a guest VM.Affected if Untrusted or low-privileged users have access to any guest virtual machine running on this Parallels installation
You are affected if Parallels Desktop is exactly version 16.0.1 with build 48919 or earlier, and the Toolgate component is enabled for guest-host communication.
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 dataApply the vendor patch by updating Parallels Desktop to a version beyond 16.0.1-48919. Ensure guest VMs are tested post-update to confirm the patch does not introduce regressions.
- Consultation2.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27244 — 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-2021-27244 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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