CVE-2020-9844
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 double free issue was addressed with improved memory management. This issue is fixed in iOS 13.5 and iPadOS 13.5, macOS Catalina 10.15.5. A remote attacker may be able to cause unexpected system termination or corrupt 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 · moderate confidenceA double-free vulnerability in the kernel allows a remote attacker to cause unexpected system termination or corrupt kernel memory. The issue stems from improper memory management where memory is freed twice, leading to use-after-free conditions that can be exploited for code execution.
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< 13.5< 13.5>= 10.13, < 10.13.6>= 10.14, < 10.14.6>= 10.15, < 10.15.5= 10.13.6= 10.14.6CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 checksWork through these to decide whether this CVE applies to you.
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Check iOS version on iPhoneGo to Settings > General > About > Version, or run 'nsurlsessiond' logging via Console to inspect version stringAffected if Version is lower than 13.5 (for example, 13.4.1, 13.4, 13.3.1, etc.)
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Check iPadOS version on iPadGo to Settings > General > About > Version, or inspect device via Apple Configurator or MDM profileAffected if Version is lower than 13.5
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Check macOS version via System PreferencesClick Apple menu > About This Mac; the version number appears below the OS nameAffected if Version is 10.13.6, 10.14.6, or any 10.15.x version before 10.15.5; also affected are 10.13.x versions before 10.13.6 and 10.14.x versions before 10.14.6
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Check macOS version via terminalRun 'sw_vers' command in Terminal; inspect the ProductVersion outputAffected if Output shows a version matching the affected ranges: 10.13.x (before 10.13.6), 10.14.x (before 10.14.6), 10.15.x before 10.15.5, or exactly 10.13.6 or 10.14.6
You are affected if your device runs iOS/iPadOS below 13.5, or macOS Sierra/High Sierra/Catalina below the 10.13.6/10.14.6/10.15.5 security updates respectively.
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.
From vendor data10.13.610.14.610.15.5
Apply the vendor-supplied patches: iOS 13.5, iPadOS 13.5, or macOS Catalina 10.15.5 depending on the affected device. No practical workarounds exist for this kernel-level memory corruption issue.
- Consultation3.0 h
- Implementation8.0 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 $4,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9844 — 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-2020-9844 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