CVE-2016-10142

CVE-2016-10142 is a high-severity vulnerability in Ietf Ipv6 with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-17.

Key facts

Description

An 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.

Frequently asked questions

What is CVE-2016-10142?
An 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.
How severe is CVE-2016-10142?
CVE-2016-10142 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-10142 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-10142?
CVE-2016-10142 affects Ietf Ipv6. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-10142?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-10142 published?
CVE-2016-10142 was published on 2017-01-14 and last updated on 2026-06-17.

References

Affected products (1)

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