CVE Alert: CVE-2026-76476 – Cisco

As part of Cisco’s ongoing commitment to proactive security and product quality, engineering teams for Cisco Emergency Responder, Cisco Prime Collaboration Deployment, Cisco Unified Communications Manager (Unified CM), Cisco Unified Communications Manager IM & Presence Service (Unified CM IM&P), Cisco Unified Communications Manager Session Management Edition (Unified CM SME), and Cisco Unity Connection have conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.   The vulnerabilities tracked by CVE-2026-76476 are related to issues concerning improper input validation that are grouped under the Common Weakness Enumeration (CWE) Class CWE-20.

High operational risk: remediate promptly, but the supplied data does not establish active exploitation or justify a priority-one rating.

A successful attack could compromise confidentiality, integrity and availability of communications services, disrupting calling, messaging or emergency-response workflows. That could enable service outages, unauthorised changes or access to sensitive communications; the supplied information reports no known malicious use, but KEV, SSVC and EPSS data are absent.

### Most likely attack path

An attacker needs network access and low-level privileges, but no victim interaction; low attack complexity makes exposed, reachable management or service interfaces the main concern. Scope is unchanged, so the assessed impact stays within the affected system’s authority; lateral movement is not established by the supplied metrics.

### Who is most exposed

Organisations running these communications platforms on networks reachable by users, partners or the internet are most exposed, especially where administrative access is broadly available.

Review authentication and application logs for unusual accounts, source addresses or access times.

Alert on malformed-request errors, repeated validation failures and unexpected service restarts.

Check for configuration changes or call-routing, voicemail and presence anomalies.

Correlate activity across the platform and adjacent network controls.

### Mitigation and prioritisation

Inventory deployments and apply Cisco’s relevant hardening updates promptly after compatibility testing.

Restrict management and service access to trusted hosts; remove unnecessary external reachability.

Review privileged accounts and credentials, and monitor closely until updates are complete.

Confirm KEV, SSVC and EPSS status before final urgency ranking; schedule changes with communications-service owners.

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