Cisco IP Phones Web Server Remote Code Execution and Denial-of-Service Vulnerability

Added to KEV
2021-11-03
Federal due date
2022-05-03
Vendor
Cisco
Product
Cisco IP Phones
EPSS
99.5th percentile (score 0.871, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2020-3161

CISA short description

Cisco IP Phones contain an improper input validation vulnerability for HTTP requests. Exploitation could allow an attacker to execute code remotely with root privileges or cause a denial-of-service (DoS) condition.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.