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Cisco Bug: CSCup11309 - Non MD5 HSRP Packets Processed When MD5 Configured

Last Modified

Mar 22, 2019

Products (8)

  • Cisco Nexus 7000 Series Switches
  • Cisco Nexus 7000 10-Slot Switch
  • Cisco Nexus 7000 4-Slot Switch
  • Cisco Nexus 7700 6-Slot Switch
  • Cisco Nexus 7000 18-Slot Switch
  • Cisco Nexus 7700 18-Slot Switch
  • Cisco Nexus 7000 9-Slot Switch
  • Cisco Nexus 7700 10-Slot Switch

Known Affected Releases


Description (partial)

A vulnerability in HSRP authentication of Cisco Nexus series could allow an unauthenticated, adjacent attacker to affect the state of HSRP group 
members and cause blackholing of traffic.

The vulnerability is due to incorrect parsing of malformed HSRP packets. An attacker could exploit this vulnerability by sending malformed HSRP 
packets to bypass HSRP authentication. An exploit could allow the attacker to bypass HSRP authentication and affect the state of active HSRP group 
members, causing them to go to SPEAK state and thus leading to blackholing of traffic and a denial of service (DoS) condition.

Cisco NX-OS devices configured for TEXT or MD5 group authentication will accept malformed HSRP packets leading to bypass of authentication. A 
potential attacker can affect the state of HSRP group members, causing them to release ACTIVE/STANDBY roles and go back to SPEAK state.
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Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
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  • Known Fixed Releases
  • Related Community Discussions
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