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2017-04 Security Bulletin: Junos: PFE crash while handling IPv6 ND advertisements (CVE-2017-2340)

  [JSA10786] Show Article Properties


Product Affected:
This issue can affect any M/MX platform running Junos OS where DHCPv6 subscribers are configured.
Problem:

A vulnerability in processing IPv6 ND packets originating from subscribers and destined to M/MX series routers configured with Enhanced Subscriber Management for DHCPv6 subscribers can result in a PFE (Packet Forwarding Engine) hang or crash.

The Enhanced Subscriber Management feature was introduced in Junos OS 15.1R3 for M/MX-Series devices.

On the affected Junos OS 15.1 versions, devices are vulnerable only when the system configuration contains:

subscriber-management enable force

On the affected Junos OS 16.1 versions, devices are vulnerable only when the system configuration contains:

subscriber-management enable

This issue does not affect devices with only IPv4 configured.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

No other Juniper Networks products or platforms are affected by this issue.

This issue has been assigned CVE-2017-2340.
 

Solution:
The following software releases have been updated to resolve this specific issue: Junos OS 15.1R5, 16.1R3, 16.2R1 and all subsequent releases.

This issue is being tracked as PR 1212431 and is visible on the Customer Support website.

KB16765 - "In which releases are vulnerabilities fixed?" describes which release vulnerabilities are fixed as per our End of Engineering and End of Life support policies.
 
Workaround:
It is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the router only from trusted, administrative networks or hosts.
 
Implementation:
Security vulnerabilities in Junos are fixed in the next available Maintenance Release of each supported Junos version. In some cases, a Maintenance Release is not planned to be available in an appropriate time-frame. For these cases, Service Releases are made available in order to be more timely. Security Advisory and Security Notices will indicate which Maintenance and Service  Releases contain fixes for the issues described. Upon request to JTAC, customers will be provided download instructions for a Service Release. Although Juniper does not provide formal Release Note documentation for a Service Release, a list of "PRs fixed" can be provided on request.
 
Modification History:
2017-04-12: Initial release.
2017-04-21: Updated the Problem section to state that 'force' option is not a prerequisite for this vulnerability on 16.1 releases.

 
Related Links:
CVSS Score:
4.3 (CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Risk Level:
Medium
Risk Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."