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2016-01 Security Bulletin: Junos: EX4300 Series denial of service due to artificial loop in network topology (CVE-2016-1260)



Article ID: JSA10719 SECURITY_ADVISORIES Last Updated: 12 Jan 2016Version: 1.0
Product Affected:
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 Support website.

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.

Modification History:
Modification History:

2016-01-13: Initial publication

CVSS Score:
5.3 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Severity Level:
Severity Assessment:
A network based attacker can create high network bandwidth usage denial of service condition.

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