iOSOperating system · Cisco
CVE-2011-2059
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 component in Cisco IOS before 15.1(4)M1.3 allows remote attackers to conduct fingerprinting attacks and obtain potentially sensitive information about the presence of the IOS operating system via an ICMPv6 Echo Request packet containing a Hop-by-Hop (HBH) extension header (EH) with a 0x0c01050c value in the PadN option data, aka Bug ID CSCtq02219.
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 confidenceThis vulnerability in Cisco IOS IPv6 implementation before version 15.1(4)M1.3 allows remote attackers to conduct OS fingerprinting via specially crafted ICMPv6 Echo Request packets containing a Hop-by-Hop extension header with a specific PadN option value (0x0c01050c). The attack reveals whether the target is running a vulnerable Cisco IOS version, enabling further targeted attacks.
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
iOSOperating system
< 15.1\(4\)m1.3CVSS 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
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/A:N
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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Determine the installed Cisco IOS versionRun the command 'show version' on the Cisco device and locate the IOS version string in the output (typically displayed as something like 15.1(4)M1 or similar).Affected if The version string is lower than 15.1(4)M1.3 (for example, 15.1(4)M, 15.1(3)T, 12.x, etc.)
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Verify IPv6 is enabled on the deviceRun the command 'show ipv6 interface brief' to see if any interfaces have IPv6 addresses configured. Alternatively, check the running configuration for 'ipv6 enable' or 'ipv6 address' statements under interface configurations.Affected if IPv6 is enabled and the device has IPv6 addresses configured (the vulnerability affects the IPv6 stack, so IPv6 must be active for the device to be at risk)
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Confirm ICMPv6 traffic processing is allowedCheck the device configuration with 'show running-config | include icmp' or review any access-lists applied to interfaces for IPv6 ICMP traffic. Look for any explicit 'deny icmp' statements that might block ICMPv6.Affected if ICMPv6 Echo Request packets can reach the device (no ACL blocking inbound ICMPv6 Echo Request at network edge) - this is the traffic type that triggers the fingerprinting response
The device is affected if it runs Cisco IOS version lower than 15.1(4)M1.3 AND has IPv6 enabled with ICMPv6 traffic permitted, as the vulnerability allows remote attackers to fingerprint the IOS version via crafted ICMPv6 packets.
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 data15.1
Upgrade Cisco IOS to version 15.1(4)M1.3 or later. If immediate upgrade is not feasible, consider filtering ICMPv6 traffic at network perimeter as a compensating control.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation6.0 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-2011-2059 — 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-2011-2059 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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- Version or environment caveats, and links to real fixes
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