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2016-10 Security Bulletin: Junos: IPv6 denial of service vulnerability due to resource exhaustion (CVE-2016-4921)



Article ID: JSA10762 SECURITY_ADVISORIES Last Updated: 07 Aug 2017Version: 4.0
Product Affected:
This issue can affect any product or platform running Junos OS with IPv6 enabled.
By flooding a router with specially crafted IPv6 traffic, all available resources can be consumed, leading to the inability to store next hop information for legitimate traffic.  In extreme cases, the crafted IPv6 traffic may result in a total resource exhaustion and kernel panic.  The issue is triggered by traffic destined to the router.  Transit traffic does not trigger the vulnerability.

This issue only affects devices with IPv6 enabled and configured. Devices not configured to process IPv6 traffic are unaffected by this vulnerability.

This issue was found during internal product security testing.

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

This issue has been assigned CVE-2016-4921.
The kernel panic (PR 1017099) has been addressed in Junos OS 11.4R13, 12.1X44-D45, 12.1X46-D30, 12.1X47-D20, 12.3R9, 13.3R5, and all software releases listed below.  However, a more complete IPv6 resource management improvement (PR 1037225) has addressed these resource exhaustion issues in the following software releases: 11.4R13-S3, 12.3R3-S4, 12.3X48-D30, 13.3R10*, 13.3R4-S11, 14.1R2-S8, 14.1R4-S12, 14.1R8, 14.1X53-D28, 14.1X53-D40, 14.1X55-D35, 14.2R3-S10, 14.2R4-S7, 14.2R6, 15.1F2-S5, 15.1F5-S2, 15.1F6, 15.1R3, 15.1X49-D40, 15.1X53-D57, 15.1X53-D70, 16.1R1, and all subsequent releases.

The two fixes for this issue are being tracked as PRs 1037225 and 1017099 which are 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.

*Available end of Q4/2016.
Limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the router via IPv6 only from trusted, administrative networks or hosts.
How to obtain fixed software:

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:
2016-10-12: Initial publication
2016-10-17: Added fixes for 14.1X53-D28, 14.1X55-D35, and 15.1X53-D61
2017-08-07: Additional fixed releases
CVSS Score:
7.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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