Date: 14 January 2016
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AUSCERT External Security Bulletin Redistribution
2016-01 Security Bulletin: Junos: EX4300 Series denial of
service due to artificial loop in network topology
14 January 2016
AusCERT Security Bulletin Summary
Product: Juniper EX4300 Series
Publisher: Juniper Networks
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2016-1260
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2016-01 Security Bulletin: Junos: EX4300 Series denial of service due to
artificial loop in network topology (CVE-2016-1260)
Security Advisories ID: JSA10719
Last Updated: 12 Jan 2016
This issue can affect EX4300-Series switches.
A certain type of legitimate traffic which can be maliciously crafted or may
be valid traffic for networking requirements in customer sites received from
ingress interfaces through the EX-PFE leak out blocked Spanning Tree Protocol
egress interfaces creating an artificial loop in network topology. This can
lead to a high bandwidth usage denial of service condition. Continued packets
can create a persistent denial of service condition.
This issue is most likely to occur in Virtual Chassis (VC) configurations.
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-2016-1260.
The following software releases have been updated to resolve this specific
issue: Junos OS 13.2X51-D36, 13.2X51-D39, 14.1X53-D25, 14.1X53-D26, 15.2R1 and
all subsequent releases.
This issue is being tracked as PR 1069179 and is visible on the Customer
Eliminating Spanning Tree Protocol usage from the network and blocking any
ingress or egress STP traffic may mitigate this issue.
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.
2016-01-13: Initial publication
KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin
KB16765: In which releases are vulnerabilities fixed?
KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security
Report a Security Vulnerability - How to Contact the Juniper Networks Security
Incident Response Team
EX4300 Series denial of service due to artificial loop in network topology
A network based attacker can create high network bandwidth usage denial of
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