dbcve.org
Mac Os XOperating system · Apple

CVE-2021-30876

HIGH · 7.1 CVSS v3.1 Published 2021-08-24
Fix available
A fix is available. Upgrade to 11.6.1 / 12.0.1 or later.
See remediation →
74/100
Remediation priority · Elevated
No privileges

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 was addressed with improved bounds checking. This issue is fixed in macOS Monterey 12.0.1, Security Update 2021-007 Catalina, macOS Big Sur 11.6.1. Processing a maliciously crafted AppleScript binary may result in unexpected application termination or disclosure of process 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

This is an out-of-bounds read vulnerability in macOS AppleScript interpreter caused by insufficient bounds checking when processing maliciously crafted AppleScript binary files. An attacker can craft a specially designed AppleScript binary that reads memory outside allocated buffer boundaries, potentially exposing sensitive process memory or causing application crashes.

MitigationApply the appropriate Apple security update for the macOS version in use: macOS Monterey 12.0.1, Security Update 2021-007 for Catalina, or macOS Big Sur 11.6.1. Deploy via MDM, Apple Software Update, or manual installation.

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:>= 10.15, <= 10.15.6= 10.15.7
macOSOperating system
Affected:>= 11.0, < 11.6.1>= 12.0, < 12.0.1

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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. Identify the installed macOS version
    Run `sw_vers -productVersion` in Terminal to obtain the exact macOS version number
    Affected if The version is 10.15.0 through 10.15.6, 10.15.7, 11.0 through 11.6.0, or 12.0.0
  2. Confirm AppleScript interpreter availability
    Verify osascript or System Events scripting capability is present by running `osascript -e 'return "available"'`
    Affected if The command returns "available" indicating the AppleScript interpreter is present and functional on the system
  3. Check for presence of compiled AppleScript files
    Search for .scpt or .scptd files in user-accessible directories using `find ~ -name "*.scpt" -o -name "*.scptd" 2>/dev/null`
    Affected if Compiled AppleScript binary files exist on the system and could potentially be maliciously crafted to trigger the vulnerability

The system is affected if it runs macOS 10.15.0-10.15.7, 11.0-11.6.0, or 12.0.0 and has the AppleScript interpreter available, as the vulnerability can be triggered by processing a specially crafted AppleScript binary file.

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.

dbcve · scoped
Upgrade available Upgrade to 11.6.1 / 12.0.1 or later
Fixed in 11.6.112.0.1
Interim mitigation

Apply the appropriate Apple security update for the macOS version in use: macOS Monterey 12.0.1, Security Update 2021-007 for Catalina, or macOS Big Sur 11.6.1. Deploy via MDM, Apple Software Update, or manual installation.

Recommended fix High confidence

macOS 12.0.1 (Monterey), Big Sur 11.6.1, or Security Update 2021-007 for Catalina

  1. Open System Preferences (or System Settings on macOS Monterey)
  2. Click on 'Software Update' to check for available updates
  3. For macOS 10.15 (Catalina): Install Security Update 2021-007 Catalina
  4. For macOS 11.x (Big Sur): Update to macOS Big Sur 11.6.1 or later
  5. For macOS 12.0 (Monterey): Update to macOS Monterey 12.0.1 or later
  6. Restart the system after applying the update
Caveat Users on macOS 10.15.6 or earlier must update to 10.15.7 first before applying Security Update 2021-007

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mac Os X Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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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-2021-30876 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