CVE-2025-64656 is an out-of-bounds read vulnerability classified under CWE-125 affecting Microsoft Azure Application Gateway. This vulnerability arises due to improper bounds checking within the Application Gateway's processing logic, allowing an attacker to read memory beyond allocated buffers. Such out-of-bounds reads can lead to leakage of sensitive information, which may include credentials, session tokens, or other critical data. The vulnerability is exploitable remotely over the network without requiring any authentication or user interaction, making it highly accessible to attackers. The CVSS v3.1 score of 9.4 (critical) reflects the vulnerability's high impact on confidentiality and integrity, with a low attack complexity and no privileges required. Although no public exploits have been reported yet, the potential for privilege escalation and subsequent compromise of the Application Gateway or connected backend services is significant. The Application Gateway is a widely used Azure service that manages web traffic and provides security features such as web application firewall capabilities. Exploitation could allow attackers to bypass security controls, access sensitive data, or disrupt service availability. Given the critical role of Azure Application Gateway in cloud infrastructure, this vulnerability poses a substantial risk to organizations relying on Azure for web application delivery and security. Microsoft has published the vulnerability details but has not yet released patches, emphasizing the need for vigilance and interim mitigations.

For European organizations, the impact of CVE-2025-64656 is substantial due to the widespread adoption of Microsoft Azure cloud services across the region. Organizations using Azure Application Gateway for managing web traffic and securing applications could face unauthorized data disclosure, privilege escalation, and potential lateral movement within their cloud environments. This could lead to breaches of sensitive personal data protected under GDPR, resulting in regulatory penalties and reputational damage. The vulnerability could also disrupt critical business operations by compromising the integrity and availability of web applications. Sectors such as finance, healthcare, government, and critical infrastructure, which heavily depend on secure cloud services, are particularly at risk. The ease of exploitation without authentication increases the likelihood of attacks, including from nation-state actors or cybercriminal groups targeting European entities. Furthermore, the potential for attackers to leverage this vulnerability to bypass security controls could undermine trust in cloud service providers and complicate incident response efforts.

Until an official patch is released by Microsoft, European organizations should implement several specific mitigations to reduce risk. First, restrict network exposure of the Azure Application Gateway by limiting inbound traffic to trusted IP ranges and enforcing strict firewall rules. Enable and closely monitor Azure security logs and network traffic for unusual patterns indicative of exploitation attempts. Employ Azure-native security features such as Web Application Firewall (WAF) policies to detect and block suspicious requests. Conduct thorough vulnerability scanning and penetration testing focused on the Application Gateway to identify potential exploitation vectors. Implement strict identity and access management (IAM) policies to minimize privileges associated with the Application Gateway service. Consider deploying additional network segmentation to isolate critical backend services from the gateway. Maintain regular communication with Microsoft for updates on patch availability and apply security updates immediately upon release. Finally, prepare incident response plans tailored to potential exploitation scenarios involving this vulnerability.