CVE-2025-27827 identifies a vulnerability in the legacy chat component of Mitel MiContact Center Business versions up to 10.2.0.3. The flaw arises from improper handling of session data within the chat functionality, which can be exploited by an unauthenticated attacker. Exploitation requires user interaction, such as a victim engaging with a maliciously crafted chat message or link. Successful exploitation allows the attacker to conduct an information disclosure attack, gaining unauthorized access to active chat rooms. This includes the ability to read sensitive chat data and send messages within ongoing chat sessions, effectively impersonating legitimate users or injecting misleading information. The vulnerability compromises confidentiality and integrity of communications within the affected system. Since the chat component is legacy, it may lack modern security controls, increasing the risk of exploitation. No CVSS score or patches are currently available, and no known exploits have been observed in the wild. The vulnerability affects a widely used customer contact and communication platform, which is critical for business operations involving customer support and internal communications.

For European organizations, the impact of this vulnerability could be significant, particularly for those relying on Mitel MiContact Center Business for customer service and internal communications. Unauthorized access to chat sessions could lead to leakage of sensitive customer information, including personal data protected under GDPR, resulting in regulatory penalties and reputational damage. Attackers could manipulate chat conversations, potentially misleading customers or employees, causing operational disruptions or fraud. The integrity of customer interactions and internal communications would be undermined, affecting trust and service quality. Additionally, organizations in regulated sectors such as finance, healthcare, and telecommunications could face heightened risks due to the sensitivity of the data exchanged via these chat systems. The requirement for user interaction limits automated exploitation but does not eliminate risk, especially in environments with high volumes of chat traffic and users less aware of social engineering tactics.

To mitigate this vulnerability, European organizations should prioritize upgrading Mitel MiContact Center Business to versions beyond 10.2.0.3 once patches become available. In the interim, organizations should implement strict network segmentation to isolate the chat component from critical systems and sensitive data repositories. Deploying Web Application Firewalls (WAFs) with custom rules to detect and block anomalous chat session behaviors or injection attempts can reduce risk. User awareness training focusing on social engineering and phishing risks related to chat interactions is essential to minimize the likelihood of user interaction-based exploitation. Monitoring and logging chat session activities for unusual access patterns or message anomalies can aid in early detection of exploitation attempts. Organizations should also review and enforce strict session management policies, including session timeouts and re-authentication requirements for sensitive operations within the chat system. Finally, consider disabling or restricting legacy chat components if they are not essential to business operations until a secure update is applied.