Cisco Unified Communications Products Security Hardening Release: October 2026
cisco-sa-voice-hardening-twgbH9e3
Summary
A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE 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 handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device.
A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability. Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability. There is a mitigation that addresses this vulnerability.
Security Impact Rating: High CVE: CVE-2026-20301
Products covered
A separate affected-products list was not included in the collected bulletin.
Remediation
Cisco has released software updates that address this vulnerability.
CVEs in this advisory 1
Updates
- Published by Cisco
The publication date reported by the vendor.
- Added to SecurityAlert
We collected the advisory from the official source.
- Confirmed at the source
Our collector saw this advisory during a later source check.