Cisco Security Advisories Address XSS and Remote Code Execution Vulnerabilities

Executive Summary

Cisco has released security advisories addressing vulnerabilities in Cisco Unified Communications Manager and Cisco UCS Central Software. CVE-2026-76419 (CVSS 6.1) could allow unauthenticated attackers to conduct cross-site scripting attacks against users of the Unified Communications Manager interface. CVE-2026-76506 (CVSS 7.6) could enable authenticated attackers to execute arbitrary commands, modify files or access sensitive information through the UCS Central management interface. Organisations should identify affected deployments and upgrade to fixed software releases.

Key Details

Affected Platform

Cisco Unified Communications Manager, Unified CM Session Management Edition and Cisco UCS Central Software.

Attack Surface

Web-based management interfaces.

Recommended Action

Apply Cisco security updates and restrict access to management interfaces.

Affected Environment

CVE-2026-76419 affects Cisco Unified Communications Manager (Unified CM) and Unified Communications Manager Session Management Edition (Unified CM SME).

The report identifies release 15SU5 as the first fixed release for version 15. Organisations running release 14 are advised to migrate to a fixed release.

CVE-2026-76506 affects Cisco UCS Central Software. The first fixed release for version 2.1 is 2.1(2c), while installations running version 2.0 or earlier must migrate to a fixed release.

Both vulnerabilities affect their respective products regardless of device configuration.

Operational Impact

Successful exploitation of the Unified Communications Manager vulnerability could allow attackers to execute malicious scripts within a user's browser session or access sensitive browser-based information.

Exploitation of the UCS Central vulnerability could allow an authenticated attacker to execute arbitrary commands, write files to the affected system and retrieve sensitive information.

These vulnerabilities may compromise management-system security, expose sensitive operational information and increase the risk of unauthorised administrative activity.

Technical Root Cause

CVE-2026-76419 (CVSS 6.1) is a cross-site scripting vulnerability caused by insufficient validation of user-supplied input in the Cisco Unified Communications Manager web management interface.

An unauthenticated attacker could exploit the issue by persuading a user to open a specially crafted link, causing malicious script execution within the affected interface.

CVE-2026-76506 (CVSS 7.6) is a remote code execution and information disclosure vulnerability in Cisco UCS Central Software.

The flaw results from insufficient validation of user-supplied HTTP request parameters. An attacker with valid credentials could submit crafted requests to execute commands, write files or obtain sensitive information.

Recommended Mitigation

Identify affected Cisco Unified CM, Unified CM SME and UCS Central deployments.
Upgrade affected software to the appropriate fixed releases.
Migrate unsupported or older versions where necessary.
Restrict management interfaces to trusted administrative networks.
Enforce least-privilege access and review administrative permissions.
Monitor authentication logs, management activity and unexpected configuration changes.
Centralise security logs to support threat detection and incident investigation.
Use vulnerability management solutions to verify remediation and identify remaining exposure.

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References

Cisco — Unified Communications Manager XSS advisory

Cisco — UCS Central remote code execution advisory