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Advisory severityHigh7.5Cisco

High [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

This high-severity Cisco advisory covers CVE-2026-20281 affecting Session Initiation Protocol (SIP) Software.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

cisco-sa-phone-dos-txMYNRzv Source published Source updated

VulniPulse record published Record updated

CVE-2026-20281
Affected products & platforms
CiscoUnclassified
Open source advisory

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Summary

An unauthenticated remote attacker could exploit a flaw 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 to cause a denial of service (DoS) condition on an affected device.

The flaw is caused by improper memory management when an affected device processes HTTP packets.

Affected versions
  • Scope: This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco SIP Software, are registered to Cisco Unified CM, and have Web Access enabled:
  • 4.1(1)SR1 and earlier — Migrate to a fixed release
  • Release 5 (first fixed: 5.0(1))
  • Earlier than 14.4 — Migrate to a fixed release
  • Release 14.4 (first fixed: 14.4(1)SR3)
  • Release 14.4 (first fixed: 14.4(1)SR4)
  • Earlier than 11.0 — Migrate to a fixed release
  • Release 11.0 (first fixed: 11.0(6)SR8)

Official advisory · high-confidence parse· fetched 22 days ago·verify at source

Fixed versions
  • 5.0(1)
  • 14.4(1)SR3
  • 14.4(1)SR4
  • 11.0(6)SR8

Official advisory · high-confidence parse· fetched 22 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Upgrade to the first fixed release for your train per the Fixed Releases table in this advisory.
  • Release 4.1(1)SR1 and earlier: migrate to a fixed release.
  • Release 5: upgrade to 5.0(1).
  • Earlier than 14.4: migrate to a fixed release.
  • Release 14.4: upgrade to 14.4(1)SR3.
  • Earlier than 14.4: migrate to a fixed release.
  • Release 14.4: upgrade to 14.4(1)SR4.
  • Earlier than 11.0: migrate to a fixed release.
  • Release 11.0: upgrade to 11.0(6)SR8.
Temporary workarounds
  • There are no workarounds that address this vulnerability. However, disabling Web Access mitigates this vulnerability.
  • To disable Web Access on a specific device, follow these steps:
  • Log in to the Unified CM to which the phone is registered using administrative privileges, which allow modification of devices.
  • Choose Device > Phone.
  • Enter the search criteria in the search box and click Find.
  • Choose the appropriate device from the Device Name list.
  • Under Web Access, use the toggle button to choose Disabled.
  • Click Save.
  • To verify that Web Access has been disabled, enter the IP address of the phone into a browser window on a device that has internet access, and click Enter. If the IP address is unreachable, Web Access has been disabled.
  • To disable Web Access on multiple devices, use the Bulk Admin Tool (BAT) as detailed in the Bulk Administration Guide for Cisco Unified Communications Manager.

Official advisory · high-confidence parse· fetched 22 days ago·verify at source

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