CVE-2025-36117 is a session fixation vulnerability identified in IBM Db2 Mirror for i versions 7.4, 7.5, and 7.6. The vulnerability arises because the product does not invalidate or disallow reuse of session IDs after their initial use. This flaw allows an authenticated user to potentially reuse a session ID associated with another user, thereby impersonating that user within the system. The underlying weakness is classified under CWE-384 (Session Fixation), which occurs when a system accepts a session identifier from an untrusted source and does not properly invalidate it after authentication or use. In this case, the session management mechanism in Db2 Mirror for i fails to regenerate or invalidate session tokens upon user authentication or session termination, enabling attackers to hijack or fixate sessions. The vulnerability requires the attacker to have some level of authenticated access (PR:L - privileges required: low) but does not require user interaction (UI:N). The attack vector is network-based (AV:N), meaning exploitation can be attempted remotely. The CVSS v3.1 base score is 6.3, indicating a medium severity level, with impacts on confidentiality, integrity, and availability, though these impacts are limited to the scope of the compromised session. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on configuration changes or monitoring until official fixes are released. This vulnerability could be exploited to gain unauthorized access to sensitive data or perform unauthorized actions within the Db2 Mirror for i environment by impersonating other users, potentially leading to data breaches or disruption of database services.

For European organizations using IBM Db2 Mirror for i, this vulnerability poses a moderate risk. Db2 Mirror for i is often deployed in enterprise environments for high availability and disaster recovery of IBM i databases. Exploitation could allow attackers with low-level credentials to escalate privileges by session hijacking, leading to unauthorized data access or manipulation. This can compromise confidentiality of sensitive business data, integrity of database transactions, and availability of critical database services. Given the importance of data protection under GDPR, unauthorized access or data breaches resulting from this vulnerability could lead to regulatory penalties and reputational damage. Additionally, organizations relying on Db2 Mirror for i for critical operations may face operational disruptions if attackers manipulate sessions to cause denial of service or data corruption. The lack of user interaction requirement and network-based attack vector increases the risk of remote exploitation within corporate networks or via exposed interfaces. However, the requirement for some authenticated access limits the attack surface to insiders or compromised accounts. Overall, the vulnerability could facilitate lateral movement and privilege escalation within affected environments, making it a significant concern for European enterprises with IBM i infrastructure.

To mitigate CVE-2025-36117, European organizations should implement the following specific measures: 1) Immediately review and restrict user privileges to ensure minimal access rights, reducing the risk of low-privilege users exploiting session fixation. 2) Monitor session management logs for unusual session reuse or anomalies indicative of session fixation attempts. 3) Enforce strong authentication mechanisms, such as multi-factor authentication (MFA), to reduce the risk of compromised credentials enabling exploitation. 4) Apply network segmentation and firewall rules to limit access to Db2 Mirror for i management interfaces only to trusted hosts and administrators. 5) Until official patches are available, consider implementing custom session management controls or scripts that invalidate session IDs after use, if feasible. 6) Educate administrators and users about the risks of session fixation and encourage prompt reporting of suspicious activity. 7) Stay alert for IBM security advisories and apply patches or updates as soon as they are released. 8) Conduct regular security assessments and penetration testing focused on session management to identify and remediate weaknesses proactively.