CVE-2025-64657 is a stack-based buffer overflow vulnerability classified under CWE-121, discovered in Microsoft Azure Application Gateway. This vulnerability allows an attacker with no prior authentication to remotely execute arbitrary code by sending specially crafted network packets to the Azure App Gateway. The overflow occurs due to improper bounds checking on stack buffers, which can be exploited to overwrite return addresses or control data on the stack, leading to privilege escalation and full system compromise. The vulnerability impacts confidentiality, integrity, and availability, as attackers can gain control over the gateway, intercept or modify traffic, and disrupt services. The CVSS v3.1 score of 9.8 reflects its critical severity, with attack vector being network-based, no required privileges, and no user interaction needed. Although no patches or known exploits are currently available, the vulnerability's presence in a widely used cloud service component makes it a high-risk target for attackers. Azure Application Gateway is a key component in many enterprise cloud architectures, providing web traffic load balancing and security features, thus making this vulnerability particularly dangerous in multi-tenant cloud environments.

For European organizations, the impact of CVE-2025-64657 is substantial. Azure Application Gateway is widely used across Europe for secure application delivery, SSL termination, and web application firewall capabilities. Exploitation could lead to unauthorized access to sensitive data, interception or manipulation of web traffic, and disruption of critical business services. This could result in data breaches violating GDPR regulations, financial losses, reputational damage, and operational downtime. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are especially vulnerable due to the sensitive nature of their data and services. The ability to exploit this vulnerability remotely without authentication increases the risk of widespread attacks, potentially affecting multiple tenants in shared cloud environments. Additionally, the lack of available patches means organizations must rely on compensating controls until a fix is released, increasing exposure time.

Until an official patch is released, European organizations should implement several specific mitigations: 1) Restrict network access to Azure Application Gateway management interfaces and APIs using network security groups and firewall rules to limit exposure to trusted IP ranges. 2) Enable and closely monitor Azure security logs and alerts for anomalous activity indicative of exploitation attempts, such as unusual traffic patterns or privilege escalations. 3) Employ Azure-native security features like Web Application Firewall (WAF) policies to detect and block suspicious payloads that could trigger the buffer overflow. 4) Conduct thorough internal audits of Azure App Gateway configurations to ensure least privilege principles and minimize attack surface. 5) Prepare incident response plans specifically addressing potential exploitation scenarios of this vulnerability. 6) Stay informed through Microsoft security advisories and subscribe to threat intelligence feeds to rapidly deploy patches once available. 7) Consider temporary deployment of additional network segmentation or isolation for critical applications behind the gateway to contain potential breaches.