CVE-2026-20276: Cisco Ios Xr Security Vulnerability (CVSS 8.6)

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco RoomOS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20157 are related to missing encryption that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-311.

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco RoomOS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20156 are related to improper restriction of operations within the bounds of a memory buffer that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-119.

A vulnerability in the access validation of internal REST APIs of Cisco Secure Workload could allow an unauthenticated, remote attacker to access site resources with the privileges of the Site Admin role. This vulnerability is due to insufficient validation and authentication when accessing REST API endpoints. An attacker could exploit this vulnerability if they are able to send a crafted API request to an affected endpoint. A successful exploit could allow the attacker to read sensitive information and make configuration changes across tenant boundaries with the privileges of the Site Admin user. 

A vulnerability in the peering authentication in Cisco Catalyst SD-WAN Controller, formerly SD-WAN vSmart, Cisco Catalyst SD-WAN Manager, formerly SD-WAN vManage, and Cisco Catalyst SD-WAN Validator, formerly SD-WAN vBond, could allow an unauthenticated, remote attacker to bypass authentication and obtain administrative privileges on an affected system. This vulnerability exists because the peering authentication mechanism in an affected system is not working properly. An attacker could exploit this vulnerability by sending crafted requests to an affected system. A successful exploit could allow the attacker to log in to an affected Cisco Catalyst SD-WAN Controller as an internal, high-privileged, non-root user account. Using this account, the attacker could access NETCONF, which would then allow the attacker to manipulate network configuration for the SD-WAN fabric. 

A vulnerability in Cisco Catalyst SD-WAN Manager could allow an authenticated, local attacker with low privileges to gain root privileges on the underlying operating system. This vulnerability is due to an insufficient user authentication mechanism in the REST API. An attacker could exploit this vulnerability by sending a request to the REST API of the affected system. A successful exploit could allow the attacker to gain root privileges on the underlying operating system.

A vulnerability in Cisco Unified Communications Manager (Unified CM), Cisco Unified Communications Manager Session Management Edition (Unified CM SME), Cisco Unified Communications Manager IM & Presence Service (Unified CM IM&P), Cisco Unity Connection, and Cisco Webex Calling Dedicated Instance could allow an unauthenticated, remote attacker to execute arbitrary commands on the underlying operating system of an affected device.  This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending a sequence of crafted HTTP requests to the web-based management interface of an affected device. A successful exploit could allow the attacker to obtain user-level access to the underlying operating system and then elevate privileges to root.  Note: Cisco has assigned this security advisory a Security Impact Rating (SIR) of Critical rather than High as the score indicates. The reason is that exploitation of this vulnerability could result in an attacker elevating privileges to root.