CVE-2020-3161

CRITICAL KEV

Cisco IP Phone Multiple Models Firmware - Unauthenticated RCE or DoS via HTTP

Title source: llm
STIX 2.1

Exploitation Summary

CVE-2020-3161 is actively exploited and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added November 3, 2021. EIP tracks 2 public exploits from researchers including Jacob Baines, abood05972.

AI-analyzed exploit summary This exploit triggers a denial of service (DoS) in Cisco IP Phone versions before 11.7(1) by sending an excessively long activation code via a crafted HTTP request. The vulnerability is exploited through a buffer overflow in the device configuration endpoint.

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.

Exploits (2)

exploitdb WORKING POC
by Jacob Baines · textdoshardware
https://www.exploit-db.com/exploits/48342

This exploit triggers a denial of service (DoS) in Cisco IP Phone versions before 11.7(1) by sending an excessively long activation code via a crafted HTTP request. The vulnerability is exploited through a buffer overflow in the device configuration endpoint.

Classification
Working Poc 90%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Cisco IP Phone (Wireless IP Phone 8821) before 11.7(1)
No auth needed
Prerequisites: Network access to the target device · Cisco IP Phone with vulnerable firmware
devstral-2 · analyzed Feb 16, 2026 Full analysis →
nomisec WORKING POC
by abood05972 · dos
https://github.com/abood05972/CVE-2020-3161

This repository contains a functional Lua script that exploits CVE-2020-3161, a denial-of-service vulnerability in Cisco IP Phone 11.7. The exploit sends a maliciously crafted HTTP request with an excessively long 'params' value to trigger the DoS condition.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Cisco IP Phone 11.7
No auth needed
Prerequisites: Network access to the target Cisco IP Phone
devstral-2 · analyzed Feb 19, 2026 Full analysis →

Scores

CVSS v3 9.8
EPSS 0.8373
EPSS Percentile 99.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation active
Automatable yes
Technical Impact total

Details

CISA KEV 2021-11-03
VulnCheck KEV 2021-11-03
InTheWild.io 2021-07-23
ENISA EUVD EUVD-2020-24432
CWE
CWE-20
Status published
Products (31)
cisco/8831_firmware 10.3\(1\)es14
cisco/8831_firmware 11.0\(1\)
cisco/8831_firmware 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
cisco/ip_phone_8811_firmware 11.0\(1\)
cisco/ip_phone_8811_firmware 11.0\(5\)sr1
... and 21 more
Published Apr 15, 2020
KEV Added Nov 03, 2021
Tracked Since Feb 18, 2026