CVE-2021-1778
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 read issue existed in the curl. This issue was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. Processing a maliciously crafted image may lead to a denial of service.
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 confidenceAn out-of-bounds read vulnerability in curl allows processing of maliciously crafted data leading to denial of service. This was addressed with improved bounds checking and patched via Apple security updates in early 2021 across macOS, iOS, iPadOS, watchOS, and tvOS.
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< 14.4< 14.4>= 10.14, < 10.14.6>= 10.15, < 10.15.7= 10.14.6= 10.15.7>= 11.0, < 11.2< 14.4< 7.3CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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 installed curl version on the systemRun 'curl --version' in terminal and note the version number displayed (for example, 'curl 7.64.1' or similar)Affected if The curl version is earlier than the version that includes the CVE-2021-1778 fix (patched in curl 7.75.0 and later, or vendor-patched versions)
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Verify macOS version if running on MacRun 'sw_vers' in terminal and check the 'ProductVersion' line (for example, 10.15.7, 11.1, etc.)Affected if The macOS version is 10.14.x and less than 10.14.6, OR 10.15.x and less than 10.15.7, OR 11.x and less than 11.2
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Check iOS or iPadOS version on mobile deviceGo to Settings > General > About > Version on the device and note the version number (for example, 14.3, 13.7, etc.)Affected if The iOS/iPadOS version is earlier than 14.4
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Check watchOS version on Apple WatchOpen the Watch app on paired iPhone, go to General > About, and note the versionAffected if The watchOS version is earlier than 7.3
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Check tvOS version on Apple TVGo to Settings > General > About > Version on Apple TV and note the version numberAffected if The tvOS version is earlier than 14.4
A user is affected if they are running an unpatched Apple operating system (iOS < 14.4, iPadOS < 14.4, macOS < 10.14.6/10.15.7/11.2, watchOS < 7.3, tvOS < 14.4) AND have curl installed and in use on that device.
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 data7.310.14.610.15.7
Apply the relevant security updates (Security Update 2021-001 for Catalina/Mojave, macOS Big Sur 11.2, iOS/iPadOS 14.4, watchOS 7.3, tvOS 14.4) to vulnerable Apple devices or update curl installations on servers to patched versions.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1778 — 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-2021-1778 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