CVE-2025-5277 is a critical OS command injection vulnerability affecting the aws-mcp-server product developed by alexei-led. This vulnerability arises from improper input validation in the MCP server component, which allows an attacker to craft a malicious prompt. When this prompt is accessed by the MCP client, it triggers the execution of arbitrary operating system commands on the host machine running the aws-mcp-server. The vulnerability is classified under CWE-78 (Improper Neutralization of Special Elements used in an OS Command), indicating that user-supplied input is not properly sanitized before being passed to system-level command execution functions. The CVSS 4.0 base score is 9.4, reflecting a critical severity level due to the combination of network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:A). The vulnerability impacts confidentiality, integrity, and availability at a high level, as arbitrary commands can lead to data theft, system compromise, or denial of service. The scope is high, meaning the vulnerability can affect components beyond the initially vulnerable component. No known exploits are currently reported in the wild, and no patches have been published yet. The affected version is listed as '0', which likely indicates an early or initial release version of aws-mcp-server. The vulnerability was published on May 28, 2025, and was reserved just one day prior, indicating recent discovery and disclosure. The lack of patches and known exploits suggests that organizations using this product should prioritize mitigation and monitoring to prevent exploitation.

For European organizations, the impact of CVE-2025-5277 can be severe, especially for those relying on aws-mcp-server in their cloud infrastructure or management platforms. Successful exploitation could allow attackers to execute arbitrary commands remotely, potentially leading to full system compromise, data breaches, lateral movement within networks, and disruption of critical services. This could affect sectors such as finance, healthcare, manufacturing, and government agencies that depend on secure cloud management solutions. The critical nature of the vulnerability means that attackers could gain control without needing prior authentication, increasing the risk of widespread exploitation. Additionally, the requirement for user interaction (e.g., accessing a crafted prompt) means that social engineering or phishing could be used as an attack vector, which is a common tactic in targeted attacks against European enterprises. The high confidentiality, integrity, and availability impacts could result in regulatory non-compliance (e.g., GDPR), financial losses, reputational damage, and operational downtime.

Given the absence of an official patch, European organizations should implement immediate compensating controls. These include: 1) Restricting network access to the aws-mcp-server instances by implementing strict firewall rules and network segmentation to limit exposure to untrusted networks. 2) Monitoring and logging all interactions with the MCP server to detect anomalous or suspicious prompt accesses that could indicate exploitation attempts. 3) Educating users and administrators about the risk of interacting with untrusted prompts to reduce the likelihood of successful social engineering. 4) Employing application-layer filtering or web application firewalls (WAFs) that can detect and block command injection patterns in input data. 5) Conducting thorough code reviews and input validation audits if the product is customized or internally maintained. 6) Planning for rapid deployment of patches once they become available from the vendor. 7) Considering temporary disabling or isolating the aws-mcp-server component if it is not critical to operations until a fix is released. 8) Implementing endpoint detection and response (EDR) solutions to identify and respond to suspicious command execution on hosts running the vulnerable software.