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The Optical Service Module (OSM) Line Cards installed in Catalyst 6500 or Cisco 7600 chassis, and running Cisco IOS? Software Version 12.1(8)E and higher are vulnerable to a Denial of Service upon receiving a specifically constructed or corrupted packet from the local network.
Cisco has provided fixed software for this problem. The vulnerability has been assigned Cisco Bug ID CSCdy29717. |
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Credit:
The information has been provided by Cisco Systems Product Security Incident Response Team.
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Affected Products:
The following products are affected only when they have OSM Line Cards installed and running in conjunction with Cisco IOS Software Versions 12.1(8)E through 12.1(13.4)E:
* Catalyst 6500 with Sup2/MSFC2 modules
* Cisco 7600
No other releases of Cisco Catalyst hardware and software combinations are affected by this vulnerability. No other Cisco products are affected by this vulnerability.
Details:
This defect was introduced by CSCdv23236 in version Cisco IOS Software Versions 12.1(8)E. When certain malformed datagrams arrive on the interface, the packet forwarding engine specific to this line card rewrites the datagram in such a way that legitimate information is overwritten resulting in the interface ceasing to receive and forward further legitimate network traffic.
Because most networking devices typically drop the malformed datagrams, the attack must occur from a locally attached network.
Bug ID
* CSCdy29717 - Traffic forwarding stops due to packet header corruption.
Impact:
This defect causes traffic forwarding to fail, resulting in a denial of service. This can only be triggered from the local network and is not propagated across networks by most layer 3 devices.
Software Versions:
This vulnerability is repaired in version 12.1(13.5)E, and is available for general download in version 12.1(13)E1 and 12.1(12c)E2, and will be available going forward in all versions supporting this hardware combination, specifically 12.1(14)E. The 12.2S train is not affected by this vulnerability, as this particular hardware combination is not currently supported with the 12.2S software.
Obtaining Fixed Software:
Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com/public/sw-center/sw-ios.shtml.
Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with obtaining the free software upgrade(s).
Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows:
* +1 800 553 2447 (toll-free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* email: tac@cisco.com .
See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.
Please have your product serial number available and give the URL of this advisory as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.
Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades.
Workarounds:
No workarounds exist for this vulnerability. Cisco recommends upgrading to repaired versions.
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