CVE-2025-2950 is a medium-severity vulnerability affecting IBM i operating system versions 7.3, 7.4, 7.5, and 7.6, specifically within the IBM Navigator for i web interface. The vulnerability is classified under CWE-644, which involves improper neutralization of HTTP headers for scripting syntax. In this case, the IBM Navigator for i does not adequately sanitize or neutralize the Host header in incoming HTTP requests. An authenticated user with legitimate access can manipulate the Host header to inject arbitrary values, such as changing the domain or IP address referenced by the application. This manipulation can lead to unexpected behavior within the web interface, potentially enabling attacks such as web cache poisoning, redirecting users to malicious sites, or bypassing security controls that rely on the Host header for validation. Although exploitation requires authentication, the attack vector is network-based and does not require user interaction beyond sending crafted HTTP requests. The vulnerability does not directly impact availability but can affect confidentiality and integrity by enabling attackers to influence application logic or redirect traffic. No known exploits are currently reported in the wild, and no official patches have been linked yet. The CVSS v3.1 base score is 5.4, reflecting a medium severity level due to the combination of network attack vector, low attack complexity, and the requirement for privileges (authenticated user).

For European organizations using IBM i systems with the affected versions, this vulnerability poses a risk primarily to the integrity and confidentiality of their web-based management interfaces. Manipulation of the Host header could allow attackers to redirect internal management traffic, potentially leading to phishing or session hijacking scenarios if combined with other vulnerabilities or misconfigurations. Organizations relying on IBM Navigator for i for critical system administration could face risks of unauthorized command execution or data leakage if attackers exploit this flaw to influence application behavior. Given that IBM i systems are often used in industries such as finance, manufacturing, and logistics across Europe, exploitation could disrupt business operations or compromise sensitive data. However, the requirement for authentication limits the threat to insiders or attackers who have already gained some level of access, reducing the likelihood of widespread external exploitation. Still, the vulnerability could be leveraged as part of a multi-stage attack chain within compromised networks, making it a significant concern for organizations with IBM i deployments in Europe.

European organizations should implement the following specific mitigations: 1) Immediately review and restrict access to IBM Navigator for i interfaces, ensuring only trusted and necessary users have authenticated access. 2) Monitor HTTP request headers for unusual or unexpected Host header values to detect potential exploitation attempts. 3) Apply strict input validation and filtering on HTTP headers at the network perimeter or via web application firewalls (WAFs) to block manipulated Host headers before reaching the IBM Navigator for i. 4) Segment IBM i management interfaces from general network access to limit exposure. 5) Stay alert for official IBM patches or advisories addressing CVE-2025-2950 and apply them promptly once available. 6) Conduct internal audits and penetration tests focusing on header injection and related web interface vulnerabilities to identify and remediate weaknesses. 7) Educate system administrators about the risks of header manipulation and enforce strong authentication and session management practices to reduce the risk of privilege escalation.