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CVE-2020-3161: Cisco IP Phones Web Server Remote Code Execution and Denial-of-Service Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2021-11-03
• EPSS: 83.9% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-04-15 · updated 2026-06-17
• Weakness: CWE-20

Description

A vulnerability in the web server for Cisco IP Phones could allow an unauthenticated, remote attacker to execute code with root privileges or cause a reload of an affected IP phone, resulting in a denial of service (DoS) condition. The vulnerability is due to a lack of proper input validation of HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web server of a targeted device. A successful exploit could allow the attacker to remotely execute code with root privileges or cause a reload of an affected IP phone, resulting in a DoS condition.

Affected products

• Cisco 8831 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 7811 Firmware: 11.0(1)
• Cisco Ip Phone 7821 Firmware: 11.0(1)
• Cisco Ip Phone 7841 Firmware: 11.0(1)
• Cisco Ip Phone 7861 Firmware: 11.0(1)
• Cisco Ip Phone 8811 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8821-Ex Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8821 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8841 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8845 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8851 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8861 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1
• Cisco Ip Phone 8865 Firmware: 10.3(1)es14, 11.0(1), 11.0(5)sr1

References

• http://packetstormsecurity.com/files/157265/Cisco-IP-Phone-11.7-Denial-Of-Service.html
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voip-phones-rce-dos-rB6EeRXs
• http://packetstormsecurity.com/files/157265/Cisco-IP-Phone-11.7-Denial-Of-Service.html
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-voip-phones-rce-dos-rB6EeRXs
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3161

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