External risk intelligence

Cisco Unified Communications Improper Input Handling Vulnerabilities

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-76475

The affected products, including Cisco Unified Communications Manager and Unity Connection, provide enterprise communication services. While these are often deployed within internal networks, they may have web interfaces or portals that are exposed to the internet or accessible via corporate extranets depending on the organization's network architecture and configuration, making public reachability possible but not inherently guaranteed.

Cross-site Scripting

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory addresses vulnerabilities in Cisco's collaboration and communication software, specifically issues related to how web pages are generated. These weaknesses could allow for the injection of malicious content, potentially impacting the integrity and confidentiality of information processed by these systems. While the primary concern is confirming relevance and exposure within our environment, these types of vulnerabilities are generally considered significant.

Web page flaws may allow malicious content injection.
Communication systems are critical to business operations.
Confirm if our Cisco voice systems are exposed.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by tricking a user into visiting a malicious web page. This would allow the attacker to manipulate how a web page is generated, potentially leading to unauthorized actions within the affected Cisco products. The exact journey depends on the specific product and how it is configured.

Requires unauthenticated access.
Triggered by user interaction with a web page.
Risks include data compromise and unauthorized actions.

Live Threat

Current exploitation, exposure, and threat context

Improper neutralization of input during web page generation could allow an unauthenticated, remote attacker to inject malicious web scripts when a targeted user visits a malicious web page or accesses a crafted URL. This could lead to the execution of arbitrary scripts in the context of the affected web application, potentially impacting the confidentiality and integrity of the application's data or functions.

System and user data confidentiality.
Malicious scripts executed in browser.
Unauthorized actions and data exposure.

Operational Fix

Recommended remediation, mitigation, and detection steps

Cisco Unified Communications products, including Unified CM, Unity Connection, and related collaboration tools, are likely managed by specialized voice or collaboration platform teams. Initial triage involves identifying all instances of the affected software, confirming external reachability or business criticality, and then locating the platform owner for coordinated remediation.

Identify affected voice and collaboration platforms.
Verify external reachability and business criticality.
Plan remediation with platform owners.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is the software affected by CVE-2026-76475?

This vulnerability impacts several Cisco enterprise communication and collaboration tools, including Cisco Unified Communications Manager (Unified CM), Unified CM IM & Presence, Unity Connection, Emergency Responder, and Prime Collaboration Deployment. These systems are used by organizations to manage voice, video, and messaging services, acting as the backbone for internal and external business communications.

What does CVE-2026-76475 mean for my system?

CVE-2026-76475 is classified as CWE-79, or improper neutralization of input during web page generation. In plain terms, the software fails to properly filter data before displaying it on a web page. This weakness allows an attacker to inject malicious scripts into the web interface. When an unsuspecting user views that page, the script executes within their browser, potentially exposing sensitive data or performing unauthorized actions on their behalf.

How is this vulnerability triggered?

An attacker triggers this bug by tricking a user into visiting a crafted URL or a malicious web page that interacts with the vulnerable Cisco interface. It is important to note that simply having the software installed is not enough; the vulnerability requires specific user interaction. Sending traffic to the server without a user clicking a link or visiting a page does not trigger the execution of these malicious scripts.

Do I need to worry about external access to these systems?

Yes, you should assess your network configuration. According to Halo Surface Signal, these platforms are often hosted on internal networks, but their web interfaces can be reachable via the internet or corporate extranets depending on your specific setup. If your Cisco communication portals are exposed to the public internet, the potential for an attacker to reach and exploit these interfaces significantly increases.

What are the first steps to respond to this?

Begin by identifying all running instances of the affected Cisco platforms within your environment. Once identified, confirm which instances have web interfaces accessible from the internet or untrusted segments. Coordinate with the teams responsible for these communication platforms to review the latest software hardening releases from Cisco and prioritize these updates based on the system's business criticality and exposure.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-s…

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.