CVE-2025-61105 is a vulnerability identified in the FRRouting (FRR) software suite, specifically affecting versions from 4.0 through 10.4.1. The issue arises from a NULL pointer dereference in the show_vty_link_info function located in the ospf_ext.c source file. This function is involved in processing OSPF (Open Shortest Path First) protocol packets, which are used for dynamic routing in IP networks. An attacker can exploit this vulnerability by sending a specially crafted OSPF packet that triggers the NULL pointer dereference, causing the FRR process to crash and resulting in a denial of service (DoS) condition. The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the ease of exploitation (network vector, low attack complexity) and the significant impact on availability. The vulnerability is categorized under CWE-476 (NULL Pointer Dereference), which typically leads to application crashes or unexpected behavior. Although no public exploits or patches are currently available, the risk is considerable for environments relying on FRRouting for OSPF routing. The absence of confidentiality or integrity impact means the attacker cannot extract or modify data but can disrupt network routing, potentially causing outages or degraded network performance.

For European organizations, the primary impact of CVE-2025-61105 is the disruption of network availability due to the forced crash of FRRouting's OSPF routing process. This can lead to routing instability, loss of connectivity, and potential cascading failures in network infrastructure. Critical sectors such as telecommunications providers, data centers, cloud service providers, and enterprises with complex network topologies that utilize FRR for OSPF routing are particularly vulnerable. The denial of service could affect internal network operations and external connectivity, impacting business continuity and service delivery. Given the reliance on OSPF in many European networks, especially in large ISPs and governmental networks, the vulnerability could be leveraged to cause significant operational disruption. Although no data breach or integrity compromise is involved, the availability impact alone can have severe consequences, including financial losses and reputational damage. The lack of authentication requirements increases the risk of exploitation by remote attackers, including nation-state actors or cybercriminals targeting critical infrastructure.

To mitigate CVE-2025-61105, European organizations should implement the following specific measures: 1) Deploy network-level filtering and validation of OSPF packets to detect and block malformed or suspicious packets that could trigger the vulnerability. 2) Monitor OSPF traffic patterns and FRRouting process stability closely to identify early signs of exploitation or abnormal behavior. 3) Segment and isolate routing infrastructure to limit exposure to untrusted networks and reduce the attack surface. 4) Prepare for rapid deployment of patches or updates from FRRouting maintainers once available; maintain close communication with the FRR project and security advisories. 5) Consider temporary use of alternative routing protocols or redundant routing paths to maintain network resilience during remediation. 6) Conduct internal audits to inventory FRRouting deployments and assess exposure. 7) Implement incident response plans specific to routing infrastructure compromise or outages. These steps go beyond generic advice by focusing on proactive network traffic controls, monitoring, and operational readiness tailored to the nature of the vulnerability.