CVE-2020-9866
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 buffer overflow was addressed with improved bounds checking. This issue is fixed in macOS Catalina 10.15.6, Security Update 2020-004 Mojave, Security Update 2020-004 High Sierra. A buffer overflow may result in arbitrary code execution.
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 confidenceA buffer overflow vulnerability in macOS that allows arbitrary code execution. The issue was addressed through improved bounds checking in the affected component.
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< 10.15.6CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.
-
Identify the operating systemRun 'uname -a' or check System Preferences > About to confirm the system is macOSAffected if System is not macOS (this CVE applies only to macOS)
-
Determine the installed macOS versionRun 'sw_vers -productVersion' in Terminal or check System Preferences > About > VersionAffected if Version cannot be determined or is not a macOS version number
-
Compare against the vulnerable version rangeCompare the installed version to 10.15.6 - any version below 10.15.6 is affected (e.g., 10.15.5, 10.15.4, 10.14.x, etc.)Affected if Installed version is less than 10.15.6
-
Confirm the patch statusCheck if Security Update 2020-004 or later has been applied via System Preferences > Software Update, or run 'defaults read /Library/Preferences/com.apple.SoftwareUpdate.plist LastSuccessfulDate'Affected if System is below 10.15.6 and no corresponding security update has been installed
The environment is affected if the system runs macOS with a version lower than 10.15.6 and has not received the corresponding security update.
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.
dbcve · scoped10.15.6
Apply the available Apple security updates: macOS Catalina 10.15.6, Security Update 2020-004 Mojave, or Security Update 2020-004 High Sierra depending on the affected system version.
macOS Catalina 10.15.6 (or Security Update 2020-004 for Mojave/High Sierra)
- Check current macOS version by clicking the Apple menu and selecting 'About This Mac'
- If running macOS 10.15.5 (Catalina) or earlier, upgrade to macOS 10.15.6 via System Preferences > Software Update
- If running Mojave (10.14.x), install Security Update 2020-004 for Mojave
- If running High Sierra (10.13.x), install Security Update 2020-004 for High Sierra
- After installation, restart the system when prompted
- Verify the update was applied by checking About This Mac again
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9866 — 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-2020-9866 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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
- No spam, self-promotion, credentials, or personal data