Cisco IP Phones Stack-based Buffer Overflow (CVE-2025-20350)

high Tenable OT Security Plugin ID 504991

Synopsis

The remote OT asset is affected by a vulnerability.

Description

A 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 Software could allow an unauthenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to a buffer overflow when an affected device processes HTTP packets.
An attacker could exploit this vulnerability by sending crafted HTTP input to the device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. Note: To exploit this vulnerability, the phone must be registered to Cisco Unified Communications Manager and have Web Access enabled. Web Access is disabled by default.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

Solution

Refer to the vendor advisory.

Plugin Details

Severity: High

ID: 504991

Version: 1.1

Type: remote

Family: Tenable.ot

Published: 1/19/2026

Updated: 1/19/2026

Supported Sensors: Tenable OT Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v3

Risk Factor: High

Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29:sr5, cpe:/o:cisco:ip_phone_8821_firmware:11.0%280.7%29:mpp, cpe:/o:cisco:ip_phone_8821_firmware:11.0%282%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr4, cpe:/o:cisco:ip_phone_8832_firmware, cpe:/o:cisco:ip_phone_7821_firmware, cpe:/o:cisco:ip_phone_8832_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_7841_firmware, cpe:/o:cisco:ip_phone_8821_firmware:11.0%284%29:sr1, cpe:/o:cisco:ip_phone_8821_firmware:11.0%285%29:sr2, cpe:/o:cisco:ip_phone_8821_firmware:11.0%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr3, cpe:/o:cisco:ip_phone_8845_firmware, cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29:sr6, cpe:/o:cisco:ip_phone_8841_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_7841_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8861_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%285%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29:sr4, cpe:/o:cisco:ip_phone_8845_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_7811_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8811_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8865_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%284%29:sr2, cpe:/o:cisco:ip_phone_8851_firmware, cpe:/o:cisco:ip_phone_7861_firmware, cpe:/o:cisco:ip_phone_7861_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8861_firmware, cpe:/o:cisco:ip_phone_8821_firmware:11.0%282%29:sr2, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%285%29:sr1, cpe:/o:cisco:ip_phone_8861_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8821_firmware:11.0%284%29:sr3, cpe:/o:cisco:ip_phone_7821_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_7811_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8811_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29:sr1, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr5, cpe:/o:cisco:ip_phone_8865_firmware, cpe:/o:cisco:ip_phone_8821_firmware, cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29:sr2, cpe:/o:cisco:ip_phone_8821_firmware:11.0%282%29:sr1, cpe:/o:cisco:ip_phone_8832_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8811_firmware, cpe:/o:cisco:ip_phone_8865_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8841_firmware, cpe:/o:cisco:ip_phone_7821_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr2, cpe:/o:cisco:ip_phone_8841_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr6, cpe:/o:cisco:ip_phone_8845_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8851_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_8851_firmware:14.3%281%29:sr1, cpe:/o:cisco:ip_phone_8821_firmware:11.0%283%29:sr1, cpe:/o:cisco:ip_phone_8821_firmware:11.0%284%29, cpe:/o:cisco:ip_phone_8821_firmware:11.0%285%29:sr3, cpe:/o:cisco:ip_phone_7841_firmware:14.3%281%29, cpe:/o:cisco:ip_phone_7811_firmware, cpe:/o:cisco:ip_phone_8821_firmware:11.0%286%29, cpe:/o:cisco:ip_phone_7861_firmware:14.3%281%29:sr1

Required KB Items: Tenable.ot/Cisco

Patch Publication Date: 10/15/2025

Vulnerability Publication Date: 10/15/2025

Reference Information

CVE: CVE-2025-20350

CWE: 121

Detections

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