CVE-2025-49752 is a critical vulnerability classified under CWE-294 (Authentication Bypass) affecting Microsoft Azure Bastion, a managed service that provides secure and seamless RDP and SSH connectivity to virtual machines without exposing them directly to the internet. The vulnerability arises from a capture-replay attack vector, where an attacker intercepts authentication tokens or credentials during legitimate sessions and replays them to bypass authentication mechanisms. This flaw allows an unauthenticated attacker to gain elevated privileges within the Azure Bastion environment, effectively bypassing all authentication controls. The CVSS 3.1 base score of 10.0 reflects the vulnerability's characteristics: network attack vector (AV:N), no required privileges (PR:N), no user interaction (UI:N), scope change (S:C), and high impact on confidentiality (C:H), integrity (I:H), and low impact on availability (A:L). The vulnerability was reserved in June 2025 and published in November 2025, with no patches or known exploits publicly available at the time of reporting. Given Azure Bastion's role as a critical access point for cloud infrastructure, exploitation could lead to unauthorized access to virtual machines, data exfiltration, lateral movement within cloud environments, and potential disruption of cloud services. The lack of required authentication or user interaction makes this vulnerability particularly dangerous, as attackers can remotely exploit it without alerting users or administrators. The absence of patch links suggests that Microsoft has not yet released a fix, emphasizing the urgency for organizations to implement interim mitigations and monitoring.

For European organizations, the impact of CVE-2025-49752 is severe due to the widespread adoption of Microsoft Azure cloud services across the continent. Azure Bastion is commonly used to secure remote access to virtual machines, and a successful exploit would allow attackers to bypass authentication controls, leading to unauthorized access to sensitive systems and data. This could result in data breaches, intellectual property theft, disruption of critical business operations, and potential compliance violations under regulations such as GDPR. The integrity of cloud-hosted applications and data could be compromised, enabling attackers to manipulate or destroy information. Although availability impact is rated low, the potential for lateral movement and privilege escalation within the cloud environment could lead to broader cloud infrastructure compromise. The threat is particularly acute for sectors with high cloud dependency and sensitive data, such as finance, healthcare, government, and critical infrastructure. Additionally, the ease of exploitation without user interaction increases the risk of automated or large-scale attacks targeting European cloud tenants.

Until an official patch is released by Microsoft, European organizations should implement the following specific mitigations: 1) Restrict network access to Azure Bastion endpoints using Azure Firewall or Network Security Groups (NSGs) to limit exposure to trusted IP addresses only. 2) Enable and closely monitor Azure Bastion logs and Azure Monitor alerts for unusual authentication patterns or repeated connection attempts indicative of replay attacks. 3) Employ multi-factor authentication (MFA) at the Azure subscription and management levels to reduce the risk of compromised credentials being leveraged. 4) Use Just-In-Time (JIT) VM access policies to minimize the window of exposure for remote connections. 5) Conduct regular security assessments and penetration testing focused on cloud access controls and replay attack vectors. 6) Prepare incident response plans specifically addressing cloud authentication bypass scenarios. 7) Stay updated with Microsoft security advisories and apply patches immediately upon release. 8) Consider deploying additional network segmentation within Azure environments to contain potential breaches. These measures, combined with heightened vigilance, can reduce the attack surface and detect exploitation attempts before patches become available.