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AUSCERT External Security Bulletin Redistribution
Cisco Integrated Services Routers OpenSSH TCP Denial of
21 June 2016
AusCERT Security Bulletin Summary
Product: Cisco Integrated Services Routers 800, 819, and 829
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2015-6289
Comment: There are currently no patches available for this vulnerability. In
the meantime, administrators should consider risk reduction
strategies such as restricting external network access.
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Cisco Security Advisory
Cisco Integrated Services Routers OpenSSH TCP Denial of Service Vulnerability
2016 June 20 20:45 GMT
Base - 5.0
No workarounds available
Cisco Bug IDs:
A vulnerability in the handling of Secure Shell (SSH) TCP packets in the Cisco
Integrated Services Routers (ISR) models 800, 819, and 829, could allow an
unauthenticated, remote attacker to cause a partial denial of service (DoS)
condition due to low memory on the device.
The vulnerability is due to the handling of out-of-order, or otherwise
invalid, TCP packets on an SSH connection to the device. An attacker could
exploit this vulnerability by connecting via SSH to the device and then
crafting TCP packets which are out of order or have invalid flags. An exploit
could allow the attacker to cause the device to report low-memory warnings
which could in turn cause a partial DoS condition.
Cisco has not released software updates that address this vulnerability.
Workarounds that mitigate this vulnerability are not available.
This advisory is available at the following link:
Cisco ISR models 800, 819, and 829 running Cisco IOS Software Release 15.5(3)M
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this
Workarounds are not available.
Cisco provides information about fixed software in Cisco bugs, which are
accessible through the Cisco Bug Search Tool.
When considering software upgrades, customers are advised to consult the Cisco
Security Advisories and Responses archive at http://www.cisco.com/go/psirt and
review subsequent advisories to determine exposure and a complete upgrade
In all cases, customers should ensure that the devices to be upgraded contain
sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release. If
the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance providers.
Exploitation and Public Announcements
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any
public announcements or malicious use of the vulnerability that is described
in this advisory.
Version Description Section Status Date
1.0 Initial public release. - Final 2016-June-20
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS
LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO
CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information or
contain factual errors. The information in this document is intended for end
users of Cisco products.
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