dbcve.org
Mac Os XOperating system · Apple

CVE-2021-30877

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

An out-of-bounds read vulnerability exists in macOS AppleScript interpreter due to insufficient bounds checking. Processing a maliciously crafted AppleScript binary allows an attacker to read beyond allocated buffer boundaries, potentially exposing sensitive process memory or causing application termination.

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

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. Check installed macOS version
    Run 'sw_vers -productVersion' or 'system_profiler SPSoftwareDataType' in Terminal to determine the exact macOS release
    Affected if Version is 10.15.7, between 10.15 and 10.15.6 inclusive, between 11.0 and 11.6.0 inclusive, or between 12.0 and 12.0.0 inclusive
  2. Confirm AppleScript interpreter presence
    Verify the osascript command is available by running 'which osascript' or 'osascript -e ""' in Terminal
    Affected if The osascript interpreter is present on the system (default on macOS) and the version check above shows an affected macOS version
  3. Identify AppleScript binary processing context
    Determine if scripts or applications that process AppleScript binaries from untrusted sources are in use. Check for third-party apps that parse .scpt or .applescript files, or review system cron/launchd jobs for osascript calls.
    Affected if Affected macOS version AND the system or its applications process AppleScript binaries from untrusted or external sources

You are affected if running macOS 10.15.7, 10.15.x where x<=6, 11.0-11.6.0, or 12.0-12.0.0 AND untrusted AppleScript binaries can be processed by the system.

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: Monterey 12.0.1, Security Update 2021-007 for Catalina, or Big Sur 11.6.1.

Recommended fix High confidence

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

  1. Check current macOS version by clicking Apple menu > About This Mac
  2. Back up important data using Time Machine before applying updates
  3. Open System Preferences (or System Settings on macOS Ventura and later)
  4. Click on Software Update
  5. Install any available updates - for macOS 10.15.x install Security Update 2021-007 Catalina, for macOS 11.x upgrade to 11.6.1 or later, for macOS 12.x upgrade to 12.0.1 or later
  6. Restart the computer when prompted to complete the installation

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

Fix this in Mac Os X Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

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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-2021-30877 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