CVE-2020-9818
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 · uneditedAn out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.
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 confidenceThis is an out-of-bounds write vulnerability in Apple Mail for iOS, iPadOS, and watchOS. The vulnerability is triggered when processing a maliciously crafted email message, leading to memory corruption that could allow arbitrary code execution or application termination.
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< 12.4.7>= 13.0, < 13.5< 6.2.5CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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 iOS version on iPhoneOn the iPhone, go to Settings > General > About and note the version number under 'Version'Affected if The version is 12.4.6 or earlier, OR 13.0 to 13.4.x (any version below 13.5)
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Check iPadOS version on iPadOn the iPad, go to Settings > General > About and note the version number under 'Version'Affected if The version is any version below 13.5 (iPadOS was introduced with version 13.1)
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Check watchOS version on Apple WatchOn the paired iPhone, open the Watch app, go to General > About, and note the watchOS versionAffected if The version is any version below 6.2.5
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Confirm Mail app is enabledVerify that the Mail app is configured or in use on the device. Check Settings > Mail or that the app exists in the app libraryAffected if The Mail app is present and can process incoming email (this is the default state on iOS/iPadOS)
The device is affected if it runs iOS/iPadOS versions below 13.5, iOS 12.4.6 or earlier, or watchOS versions below 6.2.5, and the Mail app is enabled.
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 · scoped6.2.512.4.713.5
Apply the vendor-supplied security updates: upgrade to iOS 13.5/iPadOS 13.5, iOS 12.4.7, or watchOS 6.2.5 or later.
iOS 13.5 / iPadOS 13.5 / iOS 12.4.7 / watchOS 6.2.5 or later
- Identify the device model and current iOS/iPadOS/watchOS version via Settings > General > About
- For iPhone: If running iOS 12.x, upgrade to iOS 12.4.7. If running iOS 13.x, upgrade to iOS 13.5 or later
- For iPad: If running iPadOS 13.x, upgrade to iPadOS 13.5 or later
- For Apple Watch: Upgrade to watchOS 6.2.5 or later
- Connect device to power and WiFi before initiating update
- Go to Settings > General > Software Update and install the recommended update
- After update, verify the new version is installed via Settings > General > About
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-9818 — 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-2020-9818 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