dbcve.org
Mac Os XOperating system · Apple

CVE-2020-27936

HIGH · 7.1 CVSS v3.1 Published 2021-04-02
Fix available
A fix is available. Upgrade to 11.1.0 or later.
See remediation →
73/100
Remediation priority · Elevated
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
An out-of-bounds read issue existed that led to the disclosure of kernel memory. This was addressed with improved input validation. This issue is fixed in macOS Big Sur 11.1, Security Update 2020-001 Catalina, Security Update 2020-007 Mojave. A local user may be able to cause unexpected system termination or read kernel memory.

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

An out-of-bounds read vulnerability in macOS kernel allows a local authenticated user to read kernel memory contents or cause an unexpected system termination (kernel panic). The issue was addressed through improved input validation in the affected macOS versions.

MitigationApply the appropriate Apple security updates: macOS Big Sur 11.1, Security Update 2020-001 for Catalina, or Security Update 2020-007 for Mojave, depending on the installed OS version.

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
Mac Os XOperating system
Affected:< 11.1.0

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
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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. Determine installed macOS version
    Open Terminal and run: sw_vers -productVersion
    Affected if The version displayed is lower than 11.1.0 (for example 10.15.x or earlier)
  2. Verify macOS build matches unpatched state
    Run: uname -a to confirm kernel version and check system profiler for detailed OS build number
    Affected if Running a kernel version prior to the fixes included in macOS Big Sur 11.1, Security Update 2020-001, or Security Update 2020-007
  3. Confirm local user access exists
    Verify that a local user account exists on the system (check /Users directory or run: dscl . list /Users)
    Affected if A local authenticated user account is present on the affected macOS version

The system is affected if it is running any version of macOS earlier than 11.1.0 and has local user accounts, since the kernel vulnerability can be exploited by a local authenticated user to read kernel memory or cause a kernel panic.

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.

From vendor data
Upgrade available Upgrade to 11.1.0 or later
Fixed in 11.1.0
Interim mitigation

Apply the appropriate Apple security updates: macOS Big Sur 11.1, Security Update 2020-001 for Catalina, or Security Update 2020-007 for Mojave, depending on the installed OS version.

Fix this in Mac Os X Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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Scan for this in your stack

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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-2020-27936 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