CVE-2025-54113 is a heap-based buffer overflow vulnerability identified in the Windows Routing and Remote Access Service (RRAS) component of Microsoft Windows Server 2019, specifically version 10.0.17763.0. The vulnerability arises from improper handling of input data in RRAS, which leads to a heap overflow condition. This flaw allows an unauthenticated attacker to send specially crafted network packets to the RRAS service, triggering the overflow and enabling remote code execution (RCE) on the affected server. The vulnerability is classified under CWE-122, indicating a heap-based buffer overflow, which typically allows attackers to overwrite memory, corrupt data structures, or execute arbitrary code. The CVSS v3.1 base score of 8.8 reflects high severity, with attack vector being network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The impact scope is unchanged (S:U), with high confidentiality, integrity, and availability impacts (C:H/I:H/A:H). Although no public exploits are currently known, the vulnerability's nature and ease of exploitation make it a critical concern for administrators. RRAS is commonly used to provide VPN and routing services, often exposed to external networks, increasing the attack surface. The lack of available patches at the time of publication necessitates immediate attention to mitigation and monitoring strategies.

For European organizations, this vulnerability poses a significant threat to enterprise networks and critical infrastructure that utilize Windows Server 2019 with RRAS enabled. Successful exploitation could lead to full system compromise, allowing attackers to execute arbitrary code remotely, potentially leading to data breaches, service disruptions, and lateral movement within networks. Confidentiality of sensitive data could be compromised, integrity of systems and data altered, and availability of critical services disrupted. Organizations relying on RRAS for VPN or routing services, especially those exposing these services to the internet or untrusted networks, face elevated risk. The high severity and network attack vector mean that attackers can exploit this vulnerability without prior authentication, increasing the likelihood of targeted attacks or automated scanning. This could impact sectors such as finance, healthcare, government, and telecommunications across Europe, where Windows Server 2019 is widely deployed. The absence of known exploits currently provides a window for proactive defense, but this may change rapidly once exploit code becomes available.

1. Immediately inventory all Windows Server 2019 systems to identify those running version 10.0.17763.0 with RRAS enabled. 2. Restrict RRAS exposure by limiting network access to trusted internal networks and VPN endpoints; block RRAS-related ports at network perimeters where possible. 3. Implement network-level monitoring and intrusion detection systems to detect anomalous RRAS traffic patterns or malformed packets indicative of exploitation attempts. 4. Apply strict egress and ingress filtering to minimize attack surface and prevent exploitation from untrusted sources. 5. Enforce multi-factor authentication and strong access controls on systems providing RRAS services to reduce risk if exploitation attempts succeed. 6. Monitor vendor advisories closely and deploy security patches immediately upon release. 7. Conduct regular security assessments and penetration tests focusing on RRAS and related network services. 8. Educate IT staff about this vulnerability and ensure incident response plans include procedures for potential exploitation scenarios. 9. Consider temporary disabling RRAS services if feasible until patches are available and tested. 10. Use endpoint protection solutions capable of detecting exploitation attempts targeting heap-based buffer overflows.