Cisco fixed actively exploited Unified Communications zero day

A vulnerability in the licensing features of Cisco Identity Services Engine (ISE) and Cisco ISE Passive Identity Connector (ISE-PIC) could allow an authenticated, remote attacker with administrative privileges to gain access to sensitive information. This vulnerability is due to improper parsing of XML that is processed by the web-based management interface of Cisco ISE and Cisco ISE-PIC. An attacker could exploit this vulnerability by uploading a malicious file to the application. A successful exploit could allow the attacker to read arbitrary files from the underlying operating system that could include sensitive data that should otherwise be inaccessible even to administrators. To exploit this vulnerability, the attacker must have valid administrative credentials.

CVE-2026-20045 is an unauthenticated, remote command-execution flaw in Cisco Unified Communications Manager (including Session Management Edition), Unified CM IM & Presence Service, Unity Connection, and Webex Calling Dedicated Instance. It is caused by improper validation of user-supplied input in HTTP requests, and is triggered by sending a sequence of crafted HTTP requests to the web-based management interface of an affected device. A successful exploit gives the attacker user-level access to the underlying operating system, which can then be elevated to root — the reason Cisco assigned a Critical Security Impact Rating on top of the 9.8 CVSS score. The affected products are core enterprise call-control and voicemail platforms used by large organizations, plus Cisco-hosted Webex Calling Dedicated Instances. The flaw is being exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2026-01-21 and news reports describe active probing, though no public proof-of-concept code is known and ransomware use is listed as unknown.

Do: Upgrade all five affected products (Unified CM, Unified CM SME, Unified CM IM&P, Unity Connection, and Webex Calling Dedicated Instance) to the fixed releases listed in Cisco's advisory, as this data does not specify version numbers. Until patched, restrict access to the web-based management interface to trusted management networks and monitor affected servers for suspicious HTTP request sequences and webshells. Federal agencies must apply vendor mitigations per CISA BOD 22-01 guidance or discontinue use, following the KEV listing of 2026-01-21.