CVE-2025-41083 is a vulnerability identified in Altitude Communication Server version 8.5.3290.0, specifically affecting the Altitude Authentication Service and Communication Server components. The root cause is improper neutralization of special elements in the HTTP Host header, classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component). An attacker can manipulate the Host header in HTTP requests to alter the base URL or redirect clients to arbitrary URLs controlled by the attacker. This manipulation can trick users into submitting their login credentials to malicious websites, effectively enabling credential theft through phishing attacks facilitated by the vulnerable server. The vulnerability does not require any authentication or privileges to exploit but does require user interaction, such as clicking a malicious link. The CVSS v4.0 score is 5.1 (medium severity), reflecting network attack vector, low complexity, no privileges required, but user interaction needed. There are no known public exploits or patches currently available. The vulnerability impacts the confidentiality of user credentials and the integrity of authentication processes by enabling redirection attacks. The affected product is used in communication infrastructures, making it a significant concern for organizations relying on Altitude Communication Server for secure communications.

For European organizations, this vulnerability poses a risk of credential theft and phishing attacks that can lead to unauthorized access to sensitive communication systems. Compromise of authentication credentials could allow attackers to impersonate legitimate users, intercept or manipulate communications, and potentially escalate attacks within the network. Organizations in sectors such as telecommunications, government, and critical infrastructure that rely on Altitude Communication Server may face operational disruptions and data breaches. The redirection capability can also undermine user trust and lead to broader social engineering campaigns. Since the vulnerability requires user interaction, targeted spear-phishing campaigns could be effective, increasing the risk for high-value targets. The lack of available patches means organizations must rely on mitigations until a fix is released, increasing exposure duration.

Organizations should implement strict validation and sanitization of HTTP Host headers at the network perimeter and within web application firewalls to detect and block suspicious header manipulations. Employing Content Security Policy (CSP) headers can help restrict redirection to trusted domains. Monitoring and logging HTTP requests for anomalous Host header values can aid in early detection of exploitation attempts. User awareness training should emphasize the risks of clicking on unsolicited or suspicious links, especially those that may redirect to login pages. Network segmentation and multi-factor authentication (MFA) can reduce the impact of credential compromise. Until a vendor patch is available, consider deploying reverse proxies or web application firewalls with custom rules to neutralize Host header injection attempts. Engage with the vendor for timely updates and patches, and apply them promptly once released.