CVE-2016-10142
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 issue was discovered in the IPv6 protocol specification, related to ICMP Packet Too Big (PTB) messages. (The scope of this CVE is all affected IPv6 implementations from all vendors.) The security implications of IP fragmentation have been discussed at length in [RFC6274] and [RFC7739]. An attacker can leverage the generation of IPv6 atomic fragments to trigger the use of fragmentation in an arbitrary IPv6 flow (in scenarios in which actual fragmentation of packets is not needed) and can subsequently perform any type of fragmentation-based attack against legacy IPv6 nodes that do not implement [RFC6946]. That is, employing fragmentation where not actually needed allows for fragmentation-based attack vectors to be employed, unnecessarily. We note that, unfortunately, even nodes that already implement [RFC6946] can be subject to DoS attacks as a result of the generation of IPv6 atomic fragments. Let us assume that Host A is communicating with Host B and that, as a result of the widespread dropping of IPv6 packets that contain extension headers (including fragmentation) [RFC7872], some intermediate node filters fragments between Host B and Host A. If an attacker sends a forged ICMPv6 PTB error message to Host B, reporting an MTU smaller than 1280, this will trigger the generation of IPv6 atomic fragments from that moment on (as required by [RFC2460]). When Host B starts sending IPv6 atomic fragments (in response to the received ICMPv6 PTB error message), these packets will be dropped, since we previously noted that IPv6 packets with extension headers were being dropped between Host B and Host A. Thus, this situation will result in a DoS scenario. Another possible scenario is that in which two BGP peers are employing IPv6 transport and they implement Access Control Lists (ACLs) to drop IPv6 fragments (to avoid control-plane attacks). If the aforementioned BGP peers drop IPv6 fragments but still honor received ICMPv6 PTB error messages, an attacker could easily attack the corresponding peering session by simply sending an ICMPv6 PTB message with a reported MTU smaller than 1280 bytes. Once the attack packet has been sent, the aforementioned routers will themselves be the ones dropping their own traffic.
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 confidenceCVE-2016-10142 is a vulnerability in the IPv6 protocol specification where attackers can send forged ICMPv6 Packet Too Big (PTB) messages with MTU smaller than 1280 bytes to trigger the generation of IPv6 atomic fragments. These atomic fragments can then be exploited for fragmentation-based attacks or cause denial-of-service when intermediate nodes or peers filter IPv6 extension headers. Even hosts implementing RFC6946 remain vulnerable to DoS attacks through this vector.
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 dataall versionsCVSS 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
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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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Verify IPv6 is enabled on the hostOn Linux: cat /proc/sys/net/ipv6/conf/all/disable_ipv6 (0=enabled). On Windows: netsh interface ipv6 show interface. On macOS: networksetup -getinfo Wi-Fi | grep IPv6Affected if IPv6 is enabled (value is 0 on Linux, shows enabled on Windows/macOS)
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Confirm the host processes ICMPv6 trafficCheck firewall rules: iptables -L -n -v (Linux) or netsh advfirewall firewall show rule name=all (Windows) for rules allowing ICMPv6-inAffected if Inbound ICMPv6 traffic is permitted through the host firewall
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Inspect current IPv6 MTU configurationOn Linux: ip -6 route show. On Windows: netsh interface ipv6 show interface. On macOS: networksetup -getinfo Wi-Fi | grep MTUAffected if MTU is set below 1280 bytes or the system has dynamically adjusted MTU based on received PTB messages
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Check for atomic fragment generation or receptionCapture IPv6 traffic with tcpdump or Wireshark looking for fragments with fragment offset 0 and more fragments flag set to 0: tcpdump -i <interface> -nn 'ip6[6] == 0 and ip6[40:2] == 0x0000'Affected if Atomic fragments (fragments with no further fragments but fragment offset 0) are observed on the network
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Verify if filtering exists for ICMPv6 PTB messages with MTU < 1280Review firewall rules specifically for ICMPv6 type 2 (Packet Too Big) messages: iptables -L INPUT -n -v -p ipv6-icmp --icmpv6-type packet-too-big (Linux)Affected if No rule explicitly drops or rate-limits ICMPv6 PTB messages with MTU values below 1280 bytes
A host is affected if IPv6 is enabled, inbound ICMPv6 PTB messages are processed, and no filtering is in place for PTB messages with MTU below 1280 bytes that could trigger atomic fragment generation.
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 dataImplement validation and rate-limiting for incoming ICMPv6 PTB messages before adjusting MTU values; filter or drop atomic fragments at network boundaries; apply RFC 6946 where possible and consider dropping ICMPv6 PTB messages with MTU below 1280 except from trusted sources.
- Consultation16.0 h
- Implementation40.0 h
- Testing24.0 h
- Review / QA12.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2016-10142 — 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-2016-10142 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
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