Cisco switches hit by reboot loops due to DNS client bug
ID: e4f2df00-78f9-5aab-a345-36d4b35974e2
STIX ID: report--e4f2df00-78f9-5aab-a345-36d4b35974e2
Feed Name: Bleeping Computer
Multiple Cisco switch models (CBS250/350, Catalyst C1200, SG350/SG350X/SG550X) are reportedly entering reboot loops due to a suspected firmware bug in the DNS client (DNSC) that treats DNS and NTP lookup failures (e.g., www.cisco.com) as fatal; onset was observed around 2 AM across many networks. Administrators have mitigated the issue by disabling DNS resolution or SNTP and blocking outbound internet access from management interfaces, while Cisco has acknowledged the problem to some customers but has not yet disclosed the root cause.
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