CVE-2021-30787
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 · uneditedThis issue was addressed with improved checks. This issue is fixed in macOS Big Sur 11.5, Security Update 2021-004 Catalina, Security Update 2021-005 Mojave. An application may be able to cause unexpected system termination or write 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 confidenceA local application could exploit insufficient validation checks in macOS Catalina, Mojave, and Big Sur (prior to 11.5) to write arbitrary data to kernel memory or trigger an unexpected system kernel panic, resulting in denial of service or potential privilege escalation.
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>= 10.14, <= 10.14.5>= 10.15, <= 10.15.6= 10.14.6= 10.15.7>= 11.0, < 11.5CVSS 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 installed macOS versionClick Apple menu > About This Mac. The version number is displayed under the macOS name (for example, 10.15.7 or 11.4).Affected if The version is 10.14.0 through 10.14.5, 10.14.6, 10.15.0 through 10.15.6, 10.15.7, or any 11.0.x version through 11.4.x.
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Confirm macOS name for version contextIn About This Mac, note the macOS name (Mojave, Catalina, or Big Sur) to determine which version range applies to your system.Affected if Running Mojave (10.14.x), Catalina (10.15.x), or Big Sur (11.0-11.4.x) without the corresponding security update applied.
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Verify if security update is installedOpen System Preferences > Security & Privacy > General. Look for any installed security updates with 2021 in the name (2021-004, 2021-005, or the Big Sur 11.5 update).Affected if No security update from 2021 has been installed on a vulnerable macOS version.
A system is affected if it runs macOS 10.14.6, 10.14.x (≤10.14.5), 10.15.7, 10.15.x (≤10.15.6), or macOS 11.0-11.4.x without the July 2021 security updates applied.
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 · scoped11.5
Apply the appropriate Apple security update: macOS Big Sur 11.5, Security Update 2021-004 Catalina, or Security Update 2021-005 Mojave, depending on the macOS version in use.
macOS Big Sur 11.5, Security Update 2021-004 Catalina, or Security Update 2021-005 Mojave (depending on current macOS version)
- Open System Preferences (or System Settings on macOS 11+)
- Click on Software Update to check for available updates
- For macOS Big Sur (11.0-11.4): Install macOS Big Sur 11.5
- For macOS Catalina (10.15): Install Security Update 2021-004 Catalina
- For macOS Mojave (10.14): Install Security Update 2021-005 Mojave
- Restart the computer after installing the update
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 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 $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30787 — 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-2021-30787 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
- No spam, self-promotion, credentials, or personal data