Cisco IP Phone TCP Packet Flood Denial of Service Vulnerability [CVE-2020-3574]

CVE number – CVE-2020-3574

A vulnerability in the TCP packet processing functionality of Cisco IP Phones could allow an unauthenticated, remote attacker to cause the phone to stop responding to incoming calls, drop connected calls, or unexpectedly reload.

The vulnerability is due to insufficient TCP ingress packet rate limiting. An attacker could exploit this vulnerability by sending a high and sustained rate of crafted TCP traffic to the targeted device. A successful exploit could allow the attacker to impact operations of the phone or cause the phone to reload, leading to a denial of service (DoS) condition.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

Affected Products

  • This vulnerability affects the following Cisco IP Phones if they are running a vulnerable firmware release:
    • IP DECT 210 Multi-Cell Base Station with Multiplatform Firmware
    • IP DECT 6825 with Multiplatform Firmware
    • IP Phone 8811 Series with Multiplatform Firmware
    • IP Phone 8841 Series with Multiplatform Firmware
    • IP Phone 8851 Series with Multiplatform Firmware
    • IP Phone 8861 Series with Multiplatform Firmware
    • Unified IP Conference Phone 8831 for Third-Party Call Control
    • Webex Room Phone
  • Note: The default configurations of these devices are vulnerable.

This advisory is available at the following link:

Jason Davies

UK based technology professional, with an interest in computer security and telecoms.

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