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CVE-2026-20281

Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service Vulnerability

HIGH

7.5

CVSS Score

Published: September 2, 2026 at 04:14 PM UTC

Updated: September 2, 2026 at 07:42 PM UTC

1 product affected across 1 vendorSIP IP Phone Software

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Severity

HIGH7.5

Exploit prediction

EPSS 0.6%

SSVC

No known exploit

Description

A vulnerability in Cisco Desk Phone 9800 Series, Cisco IP Phone 7800 and 8800 Series, and Cisco Video Phone 8875 that are running Cisco Session Initiation Protocol (SIP) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper memory management when an affected device processes HTTP packets. An attacker could exploit this vulnerability by sending a continuous stream of crafted HTTP packets to the device. A successful exploit could allow the attacker to cause the affected device to continuously consume memory, resulting in a DoS condition. A manual reboot of the device is required to recover from this condition. Note: For this vulnerability to be exploitable, the phone must be registered to Cisco Unified Communications Manager (Unified CM) and have Web Access enabled. Web Access is disabled by default.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

SIP IP Phone Software · Cisco

60%

10.1(1)SR1 10.1(1)SR2 10.1(1.9)10.2(1)10.2(1)SR1 10.2(2)10.3(1)10.3(1)SR1 10.3(1)SR2 10.3(1)SR3 10.3(1)SR4 10.3(1)SR4b 10.3(1)SR5 10.3(1)SR6 10.3(1)SR7 10.3(1.11) 3rd Party 10.3(1.9) 3rd Party 10.3(2)10.4(1) 3rd Party 10.4(1)SR2 3rd Party 11-0-1MSR1-1 11.0(0.7) MPP 11.0(1)11.0(2)11.0(2)SR1 11.0(2)SR2 11.0(3)11.0(3)SR1 11.0(3)SR2 11.0(3)SR3 11.0(3)SR4 11.0(3)SR5 11.0(3)SR6 11.0(4)11.0(4)SR1 11.0(4)SR2 11.0(4)SR3 11.0(5)11.0(5)SR1 11.0(5)SR2 11.0(5)SR3 11.0(6)11.0(6)SR1 11.0(6)SR2 11.0(6)SR4 11.0(6)SR5 11.0(6)SR6 11.0(6)SR7 11.5(1)11.5(1)SR1 11.7(1)12.0(1)12.0(1)SR1 12.0(1)SR2 12.0(1)SR3 12.1(1)12.1(1)SR1 12.5(1)12.5(1)SR1 12.5(1)SR2 12.5(1)SR3 12.6(1)12.6(1)SR1 12.7(1)12.7(1)SR1 12.8(1)12.8(1)SR1 12.8(1)SR2 14.0(1)14.0(1)SR1 14.0(1)SR2 14.0(1)SR3 14.1(1)14.1(1)SR1 14.1(1)SR2 14.1(1)SR3 14.2(1)14.2(1)SR1 14.2(1)SR2 14.2(1)SR3 14.2(1)SR4 14.3(1)14.3(1)SR1 14.3(1)SR2 14.3(1)SR3 14.4(1)14.4(1)SR1 14.4(1)SR2 2.0(1)2.1(1)2.2(1)2.3(1)2.3(1)SR1 3.0(1)3.1(1)3.1(1)SR1 3.2(1)3.3(1)3.4(1)3.5(1)3.5(1)SR1 3.6(1)4.0(1)4.1(1)4.1(1)SR1 9.3(3)9.3(4) 3rd Party 9.3(4)SR1 3rd Party 9.3(4)SR2 3rd Party 9.3(4)SR3 3rd Party

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

Source: cverecord

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-dos-txMYNRzv

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHcisco

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusAWAITING ANALYSIS

CWE

CWE-401

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