PT-2025-35813 · Cisco · Cisco Desk Phone 9800 Series+3

Kent Yoder · Published 2025-09-03 · Updated 2026-01-05 · CVE-2025-20335

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Cisco Desk Phone 9800 Series Cisco IP Phone 7800 and 8800 Series Cisco Video Phone 8875

Description A vulnerability exists in the directory permissions of the affected devices, potentially allowing an unauthenticated, remote attacker to write arbitrary files on the device. This is due to a lack of proper authentication controls. An attacker could exploit this 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. To exploit this vulnerability, Web Access must be enabled on the phone.

Recommendations Ensure Web Access is disabled on the devices, as it is disabled by default.

Fix

Improper Access Control

Weakness Enumeration

CWE-284

Related Identifiers

BDU:2026-01765

CVE-2025-20335

Affected Products

Cisco Desk Phone 9800 Series

Cisco Ip Phone 7800 Series

Cisco Ip Phone 8800 Series

Cisco Video Phone 8875

References · 8

• https://bdu.fstec.ru/vul/2026-01765 · Security Note
• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-write-g3kcC5Df · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2025-20335 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2025-20335 · Security Note
• https://t.me/CVEtracker/31622 · Telegram Post
• https://t.me/cveNotify/147702 · Telegram Post
• https://twitter.com/CVEnew/status/1963298504312287429 · Twitter Post
• https://twitter.com/0dayPublishing/status/1963293259104407675 · Twitter Post