Cisco Security Advisory: Cisco IOS Software IPv6 Virtual Fragmentation Reassembly Denial of Service Vulnerability

[Cisco Systems Product Security Incident Response Team <psirt () cisco com>]

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Cisco IOS Software IPv6 Virtual Fragmentation Reassembly Denial of Service Vulnerability

Advisory ID: cisco-sa-20130925-ipv6vfr

Revision 1.0

For Public Release 2013 September 25 16:00  UTC (GMT)
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Summary
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A vulnerability in the implementation of the virtual fragmentation reassembly (VFR) feature for IP version 6 (IPv6) in 
Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload, 
resulting in a denial of service (DoS) condition.

The vulnerability is due to a race condition while accessing the reassembly queue for IPv6 fragments. An attacker could 
exploit this vulnerability by sending a crafted stream of valid IPv6 fragments. Repeated exploitation may result in a 
sustained DoS condition.

Cisco has released free software updates that address this vulnerability. There are no workarounds for this 
vulnerability.

This advisory is available at the following link: 
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-ipv6vfr

Note: The September 25, 2013, Cisco IOS Software Security Advisory bundled publication includes eight Cisco Security 
Advisories. All advisories address vulnerabilities in Cisco IOS Software. Each Cisco IOS Software Security Advisory 
lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as 
well as the Cisco IOS Software releases that correct all Cisco IOS Software vulnerabilities in the September 2013 
bundled publication.

Individual publication links are in "Cisco Event Response: Semiannual Cisco IOS Software Security Advisory Bundled 
Publication" at the following link: http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep13.html

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