CVE-2025-20335: Cisco Desk Phone 9841 Firmware

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

A vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could allow an unauthenticated, remote attacker to write arbitrary files on an affected device. This vulnerability is due to a lack of proper authentication controls. An attacker could exploit this vulnerability by sending a crafted request to an affected device. A successful exploit could allow the attacker to perform arbitrary file writes to specific directories in the underlying operating system. Note: To exploit this vulnerability, Web Access must be enabled on the phone. Web Access is disabled by default.

Affected products

Cisco Desk Phone 9841 Firmware: from 3.0\(1\), before 3.3\(1\) (fixed in 3.3\(1\))
Cisco Desk Phone 9851 Firmware: from 3.0\(1\), before 3.3\(1\) (fixed in 3.3\(1\))
Cisco Desk Phone 9861 Firmware: from 3.0\(1\), before 3.3\(1\) (fixed in 3.3\(1\))
Cisco Desk Phone 9871 Firmware: from 3.0\(1\), before 3.3\(1\) (fixed in 3.3\(1\))
Cisco IP Phone 7811 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 7821 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 7841 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 7861 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8811 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8821 Firmware: before 11.0\(6\) (fixed in 11.0\(6\)); version 11.0(6) only
Cisco IP Phone 8841 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8845 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8851 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8851nr Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8861 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco IP Phone 8865 Firmware: before 14.3\(1\) (fixed in 14.3\(1\)); version 14.3(1) only
Cisco Video Phone 8875 Firmware: before 2.3\(1\) (fixed in 2.3\(1\)); from 3.0\(1\), before 3.3\(1\) (fixed in 3.3\(1\)); version 2.3(1) only

Published 2025-09-03. Last modified 2026-06-17.