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Vulnerability record · CVE-2025-20335 · published 3 September 2025

CVE-2025-20335: Cisco desk phone 9841 firmware improper access control vulnerability

Cisco · Desk Phone 9841 Firmware

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.

5.3 CVSS 3.1 Medium EPSS 0.35% · top 73.1% CWE-284 · Improper access control
5.3CVSS 3.1 base score
0.35%EPSS exploitation probability, 30 days
NoNot in CISA KEV
17Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

17 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-write-g3kcC5Df Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2020-3161Cisco IP Phones web server input validation flaw allows root RCE and DoSThe web server on multiple Cisco IP Phone models fails to properly validate HTTP requests, allowing a crafted request to trigger remote code executio…KEVEPSS 84%analysed9.8CVE-2023-20078Cisco ip phone 6871 firmware stack-based buffer overflow vulnerabilityMultiple vulnerabilities in the web-based management interface of certain Cisco IP Phones could allow an unauthenticated, remote attacker to execute …EPSS 10%8.8CVE-2022-20968Cisco ip phone 7811 firmware out-of-bounds write vulnerabilityA vulnerability in the Cisco Discovery Protocol processing feature of Cisco IP Phone 7800 and 8800 Series firmware could allow an unauthenticated, ad…EPSS 6.1%8.8CVE-2020-3111Cisco ip conference phone 7832 firmware improper input validation vulnerabilityA vulnerability in the Cisco Discovery Protocol implementation for the Cisco IP Phone could allow an unauthenticated, adjacent attacker to remotely e…EPSS 3.1%8.1CVE-2022-20774Cisco ip phone 6871 firmware insufficient verification of data authenticity vulnerabilityA vulnerability in the web-based management interface of Cisco IP Phone 6800, 7800, and 8800 Series with Multiplatform Firmware could allow an unauth…EPSS 0.40%7.5CVE-2025-20350Cisco desk phone 9871 firmware stack-based buffer overflow vulnerabilityA vulnerability in the web UI of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 running Cisco SIP Soft…EPSS 0.48%7.5CVE-2025-20336Cisco desk phone 9841 firmware information exposure vulnerabilityA vulnerability in the directory permissions of Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 could a…EPSS 0.39%7.5CVE-2023-20079Cisco ip phone 6871 firmware stack-based buffer overflow vulnerabilityMultiple vulnerabilities in the web-based management interface of certain Cisco IP Phones could allow an unauthenticated, remote attacker to execute …EPSS 10%

Source: NIST National Vulnerability Database (record CVE-2025-20335), CISA KEV, FIRST EPSS (scores of 2026-10-09). This page is refreshed as NVD updates the record.