CISCO has released patches for 34 vulnerabilities across multiple products, including Expressway Series, IOS XR, Snort 3 and various Unified Communications components. The fixes address a range of severe issues, from remote code execution to authentication bypass and input handling flaws. Cisco states that none of the addressed vulnerabilities are known to have been exploited in the wild.
The most critical defect is a remote code execution vulnerability in Expressway Series, tracked as CVE-2026-76466. Cisco describes how persistent cookies and insufficient validation of client certificates in certain configurations could enable an attacker to connect to the database service and invoke RPC commands, potentially allowing arbitrary commands to be executed as root on the device.
Expressway Series version X15.5.20 contains the fix and also resolves eight CVEs grouped under their CWE categories, plus a medium-severity information disclosure bug. In Unified Communications, Cisco patched nine CVEs across several products including Emergency Responder, Prime Collaboration Deployment, Unified Communications Manager (CM), CM IM&P, CM SME and Unity Connection, with the most severe being CVE-2026-76473, CVE-2026-76474 and CVE-2026-76475.
Snort 3 fixes cover 13 CVEs (for example CVE-2026-20236 and CVE-2026-20043) addressing critical and high-severity issues, while IOS XR received a high-severity DoS fix for CVE-2026-76505 and a high-severity privilege-escalation issue in Secure Client’s Secure Firewall Posture (CVE-2026-76462).
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