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

View on CVE.org

Published Sep 2, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed

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 Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Cisco

Cisco Session Initiation Protocol (SIP) Software

unknown

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

No data.

Vendor Product Versions

Cisco

Session Initiation Protocol (sip) Firmware

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

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.571% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact partial

References

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

History

Nov 10, 2026 9:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Sep 3, 2026 3:45 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Cisco Cisco session Initiation Protocol (sip) Firmware
Vendors & Products		Cisco Cisco session Initiation Protocol (sip) Firmware

Sep 2, 2026 4:30 PM Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
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.
Title		Cisco Desk Phone 9800 Series, IP Phone 7800 and 8800 Series, and Video Phone 8875 with SIP Software Denial of Service Vulnerability
Weaknesses		CWE-401
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-phone-dos-txMYNRzv
Metrics		cvssV3_1 `{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}`