CVE-2025-59285 is a vulnerability classified under CWE-502 (Deserialization of Untrusted Data) found in Microsoft Azure Monitor Agent version 1.0.0. The flaw arises because the agent improperly handles deserialization of data that can be influenced by an authorized local attacker. Deserialization vulnerabilities occur when untrusted input is deserialized without sufficient validation, allowing attackers to manipulate the process to execute arbitrary code or escalate privileges. In this case, an attacker with low privileges and local access can exploit the vulnerability to elevate their privileges on the host system, potentially gaining administrative control. The attack complexity is high, meaning exploitation requires specific conditions or knowledge, and no user interaction is needed. The vulnerability affects confidentiality, integrity, and availability, as an attacker could access sensitive telemetry data, modify monitoring configurations, or disrupt monitoring services. Although no public exploits have been reported, the vulnerability is critical due to the widespread use of Azure Monitor in cloud environments. The vulnerability was reserved on September 11, 2025, and published on October 14, 2025, with no patches currently available, emphasizing the need for proactive mitigation. The CVSS v3.1 vector (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates local attack vector, high attack complexity, low privileges required, no user interaction, unchanged scope, and high impact on confidentiality, integrity, and availability.

For European organizations, this vulnerability poses a significant risk, especially for those heavily reliant on Microsoft Azure cloud services and Azure Monitor for infrastructure and application telemetry. Successful exploitation could allow attackers to gain elevated privileges on monitored systems, leading to unauthorized access to sensitive monitoring data, manipulation of telemetry, and potential disruption of monitoring capabilities. This could impair incident detection and response, increasing the risk of prolonged undetected breaches. Critical sectors such as finance, healthcare, energy, and government agencies in Europe could face severe operational and reputational damage if attackers leverage this vulnerability. Additionally, compliance with GDPR and other data protection regulations could be jeopardized due to potential unauthorized data access. The local attack vector limits remote exploitation but emphasizes the importance of securing internal access and endpoint security.

1. Monitor Microsoft’s official channels for patches addressing CVE-2025-59285 and apply them immediately upon release. 2. Restrict local access to systems running Azure Monitor Agent to trusted personnel only, employing strict access controls and multi-factor authentication for administrative accounts. 3. Implement endpoint detection and response (EDR) solutions to monitor for suspicious activities related to deserialization or privilege escalation attempts on hosts running Azure Monitor. 4. Conduct regular audits of Azure Monitor Agent configurations and logs to detect anomalies or unauthorized changes. 5. Employ application whitelisting and process integrity monitoring to prevent unauthorized code execution stemming from deserialization exploits. 6. Segment networks to limit lateral movement opportunities for attackers who gain local access. 7. Educate IT staff about the risks of deserialization vulnerabilities and the importance of limiting local privilege escalation paths. 8. Consider temporary disabling or isolating Azure Monitor Agent on critical systems if immediate patching is not feasible, balancing monitoring needs with security risks.