CVE-2025-53840 is a vulnerability identified in the Icinga DB Web interface, specifically affecting versions from 1.2.0 up to but not including 1.2.2. Icinga DB Web is a graphical front-end for the Icinga monitoring system, which is widely used for infrastructure and service monitoring. The vulnerability falls under CWE-200, which pertains to the exposure of sensitive information to unauthorized actors. In this case, users who have access to the Icinga Dependency Views can see hosts and services on the dependency map that they are not authorized to view. However, the vulnerability does not reveal the names of these objects, nor does it allow access to detailed views of the hosts or services. The issue specifically affects the enforcement of restrictions labeled as filter/hosts and filter/services, while filter/objects remains unaffected and continues to restrict access appropriately. This means that while users can see the presence of certain hosts and services they should not, they cannot identify them by name or access further details. The vulnerability requires that the user already has some level of privileges (PR:H - Privileges Required: High) and user interaction (UI:R - Required) to exploit, and it is exploitable over the network (AV:N). The vulnerability does not impact integrity or availability, only confidentiality, and has a low CVSS score of 2.4. The issue was addressed in version 1.2.2 by properly applying the intended restrictions. As a temporary workaround, downgrading to version 1.1.3 is suggested. There are no known exploits in the wild at this time.

For European organizations using Icinga DB Web versions between 1.2.0 and 1.2.1, this vulnerability could lead to unauthorized exposure of the existence of certain hosts and services within their monitored infrastructure. While the actual names and detailed information are not disclosed, the mere visibility of these objects could aid an attacker or unauthorized insider in mapping the network topology or identifying critical infrastructure components. This information leakage could facilitate further targeted attacks or reconnaissance activities. The impact on confidentiality is limited but non-negligible, especially in environments where monitoring data is sensitive or where knowledge of infrastructure layout could be leveraged by threat actors. Since exploitation requires authenticated users with high privileges and user interaction, the risk is somewhat mitigated by internal access controls. However, insider threats or compromised privileged accounts could exploit this vulnerability. The integrity and availability of the monitoring system and the monitored infrastructure are not affected. Overall, the impact is low but should not be ignored in environments with strict confidentiality requirements.

To mitigate this vulnerability, European organizations should prioritize upgrading Icinga DB Web to version 1.2.2 or later, where the access restrictions are correctly enforced. If immediate upgrading is not feasible, downgrading to version 1.1.3 is a viable temporary workaround, as this version does not exhibit the vulnerability. Additionally, organizations should review and tighten access controls to ensure that only trusted users have high privilege access to the Icinga Dependency Views. Implementing strict role-based access control (RBAC) policies and monitoring privileged user activities can reduce the risk of exploitation. Regular audits of user permissions and session monitoring can help detect unauthorized access attempts. Network segmentation and limiting access to the monitoring interface to trusted networks or VPNs can further reduce exposure. Finally, organizations should stay informed about any emerging exploits or patches related to this vulnerability and apply security updates promptly.