CVE-2025-59285: Azure Monitor Agent Privilege Escalation

CVE-2025-59285 Overview

CVE-2025-59285 is a deserialization of untrusted data vulnerability [CWE-502] in Microsoft Azure Monitor Agent. An authorized local attacker can exploit the flaw to elevate privileges on an affected host. Microsoft published the advisory on October 14, 2025 and classifies the issue as HIGH severity.

The vulnerability requires local access and low privileges, but successful exploitation compromises confidentiality, integrity, and availability of the target system. No public proof-of-concept code is available, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities catalog.

Critical Impact
A low-privileged local attacker can leverage unsafe deserialization in Azure Monitor Agent to gain elevated privileges on the host, potentially executing code in the context of the agent service.

Affected Products

Microsoft Azure Monitor Agent (Windows and Linux distributions)
Systems ingesting telemetry through Azure Monitor Agent
Azure Arc-enabled servers running the agent for hybrid monitoring

Discovery Timeline

2025-10-14 - CVE-2025-59285 published to NVD
2025-10-14 - Microsoft releases security advisory for Azure Monitor Agent
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-59285

Vulnerability Analysis

The flaw resides in how Azure Monitor Agent deserializes untrusted input during normal telemetry and configuration processing. Insecure deserialization [CWE-502] allows an attacker to supply crafted serialized objects that the agent reconstructs without adequate type or integrity validation.

When the agent processes attacker-controlled serialized data, gadget chains inside referenced libraries can trigger unintended method invocations. This chain leads to code execution in the security context of the Azure Monitor Agent service, which typically runs with elevated privileges to collect system telemetry.

The attack requires local access and authentication, but only low-level user privileges. The high attack complexity indicates that exploitation depends on race conditions, specific configurations, or precise gadget selection tied to installed components.

Root Cause

Azure Monitor Agent accepts serialized objects from a data source that a local user can influence. The deserialization routine does not restrict allowable types or validate object provenance before instantiating the object graph. This behavior maps directly to CWE-502, deserialization of untrusted data.

Attack Vector

An authenticated local attacker stages a malicious serialized payload where the Azure Monitor Agent will read it, such as a monitored file, pipe, or IPC channel. When the agent deserializes the payload, embedded gadgets execute code inside the agent process. The attacker inherits the service account privileges, enabling privilege escalation from a standard user to a higher-privileged context on the host.

No public exploitation code is currently available for this vulnerability. Refer to the Microsoft Security Update CVE-2025-59285 advisory for authoritative technical details.

Detection Methods for CVE-2025-59285

Indicators of Compromise

Unexpected child processes spawned by the Azure Monitor Agent service (AzureMonitorAgent.exe, mdsd, or amacoreagent).
Anomalous file writes or reads by the agent process in user-writable directories.
Agent service crashes, restarts, or exceptions correlated with new local user activity.

Detection Strategies

Baseline the process tree of Azure Monitor Agent and alert on deviations such as command shells, scripting hosts, or LOLBins launched from the agent.
Monitor for the agent reading serialized data from paths controlled by non-admin users.
Correlate local logon events with subsequent privilege changes on hosts running the agent.

Monitoring Recommendations

Forward agent service logs and Windows Security Event IDs 4688 and 4672 to a centralized SIEM for correlation.
Track integrity of Azure Monitor Agent binaries and configuration files using file integrity monitoring.
Review Azure Arc and Azure Monitor audit logs for unexpected configuration changes on managed hosts.

How to Mitigate CVE-2025-59285

Immediate Actions Required

Apply the Microsoft security update referenced in the MSRC advisory for CVE-2025-59285 to all affected hosts.
Inventory every system running Azure Monitor Agent, including Azure VMs, Azure Arc-enabled servers, and on-premises hosts.
Restrict interactive local logon on servers running the agent to reduce the pool of potential attackers.

Patch Information

Microsoft has published a fixed release of Azure Monitor Agent through the standard Azure update channel. Consult the Microsoft Security Update CVE-2025-59285 advisory for the exact fixed version numbers and rollout guidance for Windows and Linux platforms.

Workarounds

Enforce least-privilege access on hosts to limit local user accounts that could stage a malicious payload.
Harden file system permissions on directories read by Azure Monitor Agent so only trusted principals can write to them.
Where feasible, temporarily reduce the agent's data collection scope until patching is complete.

bash

# Verify Azure Monitor Agent version on a Windows host
Get-WmiObject -Class Win32_Product | Where-Object { $_.Name -like 'Azure Monitor Agent*' } | Select-Object Name, Version

# Verify Azure Monitor Agent version on a Linux host
dpkg -l | grep azuremonitoragent || rpm -qa | grep azuremonitoragent