CVE-2026-76476 in Emergency Responder
Summary
by MITRE • 10/21/2026
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.
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Analysis
by VulDB Data Team • 10/21/2026
Cisco has released software hardening updates for a suite of unified communications and collaboration products, including Cisco Emergency Responder, Cisco Prime Collaboration Deployment, Cisco Unified Communications Manager, its IM and Presence Service variant, Session Management Edition, and Cisco Unity Connection. These releases are the result of a comprehensive internal security review aimed at addressing multiple vulnerabilities discovered during proactive quality assurance efforts. The primary technical flaw identified across these affected products is categorized under CVE-2026-76476 and stems from improper input validation mechanisms within the application logic. This specific weakness aligns with Common Weakness Enumeration identifier CWE-20, which defines Improper Input Validation as a failure to verify or incorrectly verifies that user-supplied data conforms to expected formats, types, lengths, ranges, or other constraints before processing.
The technical nature of this vulnerability involves insufficient sanitization and validation checks on inputs received by the affected Cisco applications. When an application fails to properly validate input, it may accept maliciously crafted data structures that deviate from normal operational parameters. In the context of unified communications platforms, such inputs could potentially manipulate internal state variables, alter configuration settings, or trigger unexpected code execution paths if the validation failure allows for injection techniques or buffer overflows to occur downstream in the processing pipeline. The lack of strict boundary checks and type enforcement creates an attack surface where adversaries can exploit these gaps to bypass intended security controls embedded within the application architecture.
From an operational perspective, the impact of CWE-20 vulnerabilities varies depending on how the input is processed by the specific Cisco service involved. If exploited successfully, improper input validation could lead to a range of adverse outcomes including denial of service conditions where the system crashes or becomes unresponsive due to malformed data processing errors. In more severe scenarios involving complex parsing logic, such flaws might enable remote code execution if the invalid input leads to memory corruption or command injection vectors that are subsequently executed by privileged application processes. This poses a significant risk to the confidentiality, integrity, and availability of communication systems, potentially allowing unauthorized access to sensitive call data, configuration details, or user credentials stored within these platforms.
The classification under CWE-20 places this vulnerability within broader attack patterns often associated with injection attacks such as SQL injection, command injection, or cross-site scripting if web interfaces are involved. In the ATT&CK framework, exploitation of input validation flaws typically maps to techniques involving T1190 Exploit Public-Facing Application or potentially T1059 Command and Scripting Interpreter if code execution is achieved through injected payloads. The absence of robust defense-in-depth measures like strict output encoding or parameterized queries exacerbates the risk, allowing attackers to leverage these validation gaps for initial access or privilege escalation within the network environment hosting these Cisco services.
To mitigate the risks associated with CVE-2026-76476 and similar input validation weaknesses, organizations must prioritize the immediate application of the provided software hardening releases from Cisco. These updates contain specific code patches that enforce stricter type checking, range verification, and sanitization routines for all user-facing inputs. Beyond patching, administrators should implement network-level controls such as web application firewalls to filter out anomalous request patterns before they reach the vulnerable applications. Additionally, adhering to the principle of least privilege ensures that even if an input validation flaw is exploited, the resulting impact is contained by restricting the permissions of the service accounts running these unified communications components. Regular security audits and static code analysis during development phases are also recommended to prevent recurrence of CWE-20 issues in future software versions.