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Cisco Bug: CSCtc52299 - UDP DOS Attack HOGs CPU and Crash Router

Last Modified

Jan 28, 2017

Products (1)

  • Cisco IOS

Known Affected Releases


Description (partial)

Symptoms: UDP packets broadcast with destination port 53 for 10 minutes bring 
the CPU to 100% and cause a router crash if the dns server is removed.

Conditions: This symptom is observed with UDP broadcast at port 53, which 
causes the port to remain open and the CPU hog to occur in 5-10 minutes. The 
router CPU reaches 100% capacity and does not come down even after the 
broadcast traffic is stopped.
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