CVE-2020-3851
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 · uneditedA use after free issue was addressed with improved memory management. This issue is fixed in macOS Catalina 10.15.4, Security Update 2020-002 Mojave, Security Update 2020-002 High Sierra, macOS Catalina 10.15.3, Security Update 2020-001 Mojave, Security Update 2020-001 High Sierra. An application may be able to gain elevated privileges.
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 · moderate confidenceA use-after-free vulnerability in macOS that allows a local application to gain elevated privileges through improper memory management. The vulnerability exists in the core macOS components and can be exploited by a malicious application running on the affected system.
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>= 10.15.2, < 10.15.3>= 10.13.6, < 10.15.4CVSS 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
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/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 checksWork through these to decide whether this CVE applies to you.
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Check your macOS versionOpen Terminal and run: sw_vers -productVersionAffected if The version is 10.15.2, 10.15.3, or any 10.13.6 through 10.15.3
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Confirm the exact build numberRun: sw_vers -buildVersionAffected if The build corresponds to an unpatched version within the affected ranges
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Verify if Security Update 2020-001 or 2020-002 is installedCheck System Preferences > Security & Privacy > General for available updates, or run: defaults read /Library/Preferences/com.apple.SoftwareUpdate.plist LastSuccessfulDateAffected if No recent security update installed and system remains in an affected version range
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Confirm macOS release nameRun: sw_vers -productVersion and match to Catalina (10.15.x), Mojave (10.14.x), or High Sierra (10.13.x)Affected if Running Catalina 10.15.2 or 10.15.3, or Mojave/High Sierra below 10.15.4
Your system is affected if it runs macOS versions 10.15.2 through 10.15.3, or any version from 10.13.6 up to but not including 10.15.4, and has not received the relevant security updates.
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 data10.15.310.15.4
Apply the relevant macOS security update: macOS Catalina 10.15.4 or Security Update 2020-001/2020-002 for Mojave and High Sierra. This is a priority patch for systems with local user access.
- Consultation3.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3851 — 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-2020-3851 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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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.
- 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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