CVE-2025-15531 is a vulnerability identified in Open5GS, an open-source 5G core network implementation widely used for mobile network infrastructure. The issue resides in the sgwc_bearer_add function within the src/sgwc/context.c source file. Specifically, the vulnerability is a reachable assertion triggered by crafted input that manipulates bearer context addition logic. When exploited, this assertion failure can cause the affected process to terminate unexpectedly, resulting in denial of service (DoS) conditions. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 base score is 6.9, reflecting medium severity due to the impact on availability and ease of exploitation. The vulnerability affects Open5GS versions 2.7.0 through 2.7.5 and has been addressed in subsequent releases. While an exploit is publicly available, there are no verified reports of active exploitation in operational environments. The flaw could be leveraged by attackers to disrupt 5G core network services, impacting mobile connectivity and related services. Given Open5GS's role in 5G network infrastructure, this vulnerability poses a significant risk to telecommunications providers relying on these versions. The vulnerability does not impact confidentiality or integrity directly but can degrade service availability, which is critical for network operators.

For European organizations, particularly telecom operators and mobile network providers deploying Open5GS, this vulnerability presents a risk of service disruption through denial of service attacks. Disruption of 5G core network components can lead to degraded mobile network performance, dropped connections, and potential outages affecting end-users and enterprise customers. Critical infrastructure relying on 5G connectivity, including emergency services, IoT deployments, and industrial automation, could be indirectly impacted by network instability. The medium severity rating reflects that while the vulnerability does not allow data compromise or privilege escalation, the availability impact on core network functions can have cascading effects on business operations and service level agreements. European telecom operators with large-scale 5G deployments using vulnerable Open5GS versions are particularly vulnerable. Additionally, the public availability of an exploit increases the likelihood of opportunistic attacks, especially from threat actors targeting telecom infrastructure. The impact extends beyond individual operators to the broader digital ecosystem dependent on stable 5G connectivity.

European organizations should immediately verify their Open5GS deployment versions and upgrade to the latest patched releases beyond version 2.7.5 where this vulnerability is fixed. Network operators should implement strict network segmentation and firewall rules to restrict access to 5G core network components, limiting exposure to untrusted networks. Deploying intrusion detection and prevention systems (IDS/IPS) with signatures tuned to detect exploitation attempts targeting this vulnerability can provide early warning and block attacks. Regularly auditing and monitoring logs for anomalous bearer context addition requests can help identify exploitation attempts. Operators should also conduct thorough testing of updated Open5GS versions in staging environments before production deployment to ensure stability. Engaging with Open5GS community and security advisories for ongoing updates and patches is critical. Additionally, implementing redundancy and failover mechanisms in 5G core infrastructure can mitigate the impact of potential service disruptions. Training network operations teams on this specific vulnerability and response procedures will enhance incident readiness.