Cisco Security Advisory
OSM Line Card Header Corruption Vulnerability
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The Optical Service Module (OSM) Line Cards installed in Catalyst 6500 or Cisco 7600 chassis, and running Cisco IOSŪ 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.
The complete advisory will be available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20021211-osm-lc-ios.
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This section provides details on affected products.
Vulnerable 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:
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Catalyst 6500 with Sup2/MSFC2 modules
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Cisco 7600
Products Confirmed Not Vulnerable
No other releases of Cisco Catalyst hardware and software combinations are affected by this vulnerability. No other Cisco products are affected by this vulnerability.
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Catalyst 6500 with Sup2/MSFC2 modules
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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
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CSCdy29717 - Traffic forwarding stops due to packet
header corruption.
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CSCdy29717 - Traffic forwarding stops due to packet
header corruption.
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No workarounds exist for this vulnerability. Cisco recommends upgrading to repaired versions.
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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.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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