CVE-2011-2391
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 · uneditedThe IPv6 implementation in the kernel in Apple iOS before 7 allows remote attackers to cause a denial of service (CPU consumption) via crafted ICMPv6 packets.
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 confidenceDenial of service vulnerability in the IPv6 kernel implementation in Apple iOS versions prior to 7. Remote attackers can cause excessive CPU consumption by sending specially crafted ICMPv6 packets, leading to device resource exhaustion.
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<= 10.9.5<= 12.1<= 6.1.4= 1.0.0= 1.0.1= 1.0.2= 1.1.0= 1.1.1= 1.1.2= 1.1.3= 1.1.4= 1.1.5= 2.0= 2.0.0CVSS 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
- Adjacent
- Complexity
- Low
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:A/AC:L/Au:N/C:N/I:N/A:C
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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Identify the Apple platform in useDetermine whether the system is an iOS device (iPhone/iPad), a Mac computer, or a Windows/Mac system with iTunes installedAffected if The device runs any of the affected Apple platforms (iOS, Mac OS X, or iTunes)
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Check iOS version on iPhone or iPadOn the iOS device, go to Settings > General > About and note the Version number. Alternatively, connect the device to a computer and check in iTunes device summaryAffected if The iOS version is 6.1.4 or earlier, or matches any of these specific versions: 1.0.0, 1.0.1, 1.0.2, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 2.0, or 2.0.0
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Check Mac OS X versionClick the Apple menu > About This Mac. The version number is displayed (for example, 10.9.5)Affected if The Mac OS X version is 10.9.5 or earlier
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Check iTunes versionOpen iTunes and go to Help > About iTunes. The version number is displayed in the windowAffected if The iTunes version is 12.1 or earlier
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Verify IPv6 is enabledOn iOS: go to Settings > Wi-Fi > tap the info (i) icon > tap Configure IP > check if IPv6 is set to Automatic. On Mac: go to System Preferences > Network > select the active network interface > click Advanced > TCP/IP tab > check if IPv6 is configuredAffected if IPv6 is enabled on the device - the vulnerability only affects systems with IPv6 turned on
The system is affected if it runs a vulnerable iOS version (6.1.4 or earlier), Mac OS X (10.9.5 or earlier), or iTunes (12.1 or earlier) AND has IPv6 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.
From vendor dataUpgrade iOS devices to version 7 or later to patch the vulnerability. If immediate upgrading is not feasible, consider disabling IPv6 as a temporary workaround.
- Consultation1.0 h
- Implementation0.5 h
- Testing1.0 h
- Review / QA0.5 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-2391 — 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-2011-2391 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