CVE-2023-49208 is a critical security vulnerability identified in the Glewlwyd Single Sign-On (SSO) server, specifically affecting versions prior to 2.7.6. The vulnerability arises from a buffer overflow condition in the scheme/webauthn.c component during the FIDO2 credentials validation process in WebAuthn registration. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. In this case, the flaw is triggered during the handling of FIDO2 credential data, which is part of the Web Authentication (WebAuthn) standard used for secure passwordless authentication. Exploiting this vulnerability could allow an unauthenticated remote attacker to execute arbitrary code, cause a denial of service (DoS), or corrupt memory, leading to full compromise of the SSO server. The CVSS v3.1 base score of 9.8 reflects the high severity, with an attack vector that is network-based, requiring no privileges or user interaction, and impacting confidentiality, integrity, and availability. The vulnerability is classified under CWE-120 (Classic Buffer Overflow), a well-known and dangerous software weakness. No known exploits are currently reported in the wild, and no official patches or vendor advisories are linked yet, indicating that organizations using affected Glewlwyd versions should prioritize mitigation and monitoring. Given the critical role of SSO servers in managing authentication across multiple applications and services, successful exploitation could lead to widespread access compromise within an organization.

For European organizations, the impact of CVE-2023-49208 could be severe. Glewlwyd SSO servers are used to centralize authentication, often integrating with various internal and cloud services. A successful exploit could allow attackers to bypass authentication controls, gain unauthorized access to sensitive systems, and potentially move laterally within the network. This could lead to data breaches involving personal data protected under GDPR, intellectual property theft, disruption of business operations, and damage to organizational reputation. The critical nature of the vulnerability means that even organizations with strong perimeter defenses could be at risk if the SSO server is exposed to the internet or accessible by untrusted networks. Additionally, the lack of required authentication or user interaction for exploitation increases the risk of automated attacks. European entities in sectors such as finance, healthcare, government, and critical infrastructure, which often rely on robust authentication mechanisms, may face heightened risk due to the potential for cascading security failures following compromise of the SSO server.

To mitigate the risks posed by CVE-2023-49208, European organizations should take immediate and specific actions beyond generic advice: 1) Identify and inventory all Glewlwyd SSO server deployments within the environment, including versions in use. 2) Apply the latest available patches or updates from the Glewlwyd project as soon as they are released; if no patch is currently available, consider temporary mitigations such as disabling WebAuthn registration features or restricting access to the SSO server to trusted internal networks only. 3) Implement network-level protections such as firewall rules and segmentation to limit exposure of the SSO server to untrusted sources. 4) Monitor logs and network traffic for unusual activity related to WebAuthn registration attempts or buffer overflow indicators. 5) Conduct thorough security assessments and penetration testing focused on the SSO infrastructure to detect potential exploitation attempts. 6) Prepare incident response plans specifically addressing potential compromise of authentication infrastructure. 7) Engage with the Glewlwyd community or maintainers to stay informed about patches and advisories. These steps will help reduce the attack surface and improve detection and response capabilities.