CVE-2026-25769: Wazuh Deserialization RCE Vulnerability

CVE-2026-25769 Overview

CVE-2026-25769 is a critical Remote Code Execution (RCE) vulnerability affecting Wazuh, a free and open source platform used for threat prevention, detection, and response. The vulnerability stems from Insecure Deserialization of Untrusted Data (CWE-502) within Wazuh's cluster mode architecture.

All Wazuh deployments using cluster mode (master/worker architecture) are impacted. Organizations with a compromised worker node—whether through initial access, insider threat, or supply chain attack—face significant risk. An attacker who gains access to a worker node can achieve full RCE on the master node with root privileges, effectively compromising the entire Wazuh deployment.

Critical Impact

An attacker with access to a worker node can execute arbitrary code with root privileges on the master node, potentially compromising the entire security monitoring infrastructure.

Affected Products

• Wazuh versions 4.0.0 through 4.14.2
• Wazuh deployments using cluster mode (master/worker architecture)
• Any organization with potentially compromised worker nodes

Discovery Timeline

• 2026-03-17 - CVE-2026-25769 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2026-25769

Vulnerability Analysis

This vulnerability exploits insecure deserialization within Wazuh's cluster communication mechanism. When Wazuh operates in cluster mode, it establishes communication between master and worker nodes to coordinate security monitoring activities. The vulnerability exists because data exchanged between nodes is deserialized without proper validation, allowing malicious payloads to be processed.

The attack requires prior access to a worker node, which could be obtained through various means including initial network access, compromised credentials, insider threats, or supply chain attacks. Once an attacker has control of a worker node, they can craft malicious serialized objects that, when deserialized by the master node, result in arbitrary code execution with root privileges.

The scope-changing nature of this vulnerability means that a compromise of a worker node can directly lead to full compromise of the master node, representing a significant escalation in impact.

Root Cause

The root cause is CWE-502: Deserialization of Untrusted Data. The Wazuh cluster communication protocol deserializes data received from worker nodes without adequate validation or sandboxing. This allows an attacker with access to a worker node to inject malicious serialized objects that execute arbitrary code when processed by the master node.

The vulnerability indicates that the trust model between master and worker nodes was overly permissive, assuming that data from authenticated worker nodes would always be safe to deserialize—a dangerous assumption in environments where worker nodes may become compromised.

Attack Vector

The attack vector is network-based and requires high privileges (access to a worker node). The attack chain proceeds as follows:

1. Attacker gains access to a Wazuh worker node through initial access, credential compromise, insider threat, or supply chain attack
2. Attacker crafts a malicious serialized payload containing code to be executed
3. Malicious payload is transmitted from the worker node to the master node via cluster communication
4. Master node deserializes the payload without proper validation
5. Malicious code executes with root privileges on the master node

The vulnerability mechanism involves crafting serialized objects that exploit the deserialization process. When the master node processes cluster communication from compromised worker nodes, the malicious payload triggers code execution during the deserialization routine. Technical details are available in the GitHub Security Advisory.

Detection Methods for CVE-2026-25769

Indicators of Compromise

• Unusual or unexpected processes spawned by Wazuh master node services
• Anomalous network traffic patterns between worker and master nodes
• Unexpected file modifications or new files created with root ownership in Wazuh directories
• Evidence of serialization/deserialization errors in Wazuh cluster logs

Detection Strategies

• Monitor Wazuh master node process trees for unexpected child processes
• Implement network monitoring for anomalous cluster communication payloads
• Deploy file integrity monitoring on critical Wazuh master node directories
• Review authentication logs for unauthorized access to worker nodes
• Implement endpoint detection to identify post-exploitation activities on master nodes

Monitoring Recommendations

• Enable verbose logging for Wazuh cluster communications
• Configure alerting for new processes spawned by Wazuh services
• Monitor system calls from Wazuh master processes for suspicious activity
• Implement network segmentation monitoring between cluster nodes
• Establish baseline behavior for cluster communication patterns

How to Mitigate CVE-2026-25769

Immediate Actions Required

• Upgrade all Wazuh deployments to version 4.14.3 or later immediately
• Audit all worker nodes for signs of compromise before and after patching
• Review access controls and credentials for all Wazuh cluster nodes
• Implement network segmentation to limit lateral movement between nodes
• Enable additional monitoring on cluster communication channels

Patch Information

Wazuh has released version 4.14.3 which addresses this vulnerability. Organizations should upgrade all Wazuh components—both master and worker nodes—to the patched version. The security advisory is available at the GitHub Security Advisory page.

Before patching, organizations should conduct a thorough assessment of their worker nodes to ensure they have not been compromised, as an already-compromised worker could have exploited this vulnerability prior to remediation.

Workarounds

• If immediate patching is not possible, consider temporarily disabling cluster mode and running Wazuh in standalone mode
• Implement strict network access controls between master and worker nodes
• Deploy additional monitoring and intrusion detection on cluster communication channels
• Restrict administrative access to worker nodes to minimize compromise risk
• Consider network segmentation to isolate the Wazuh cluster from potentially compromised network segments

# Verify Wazuh version after patching
/var/ossec/bin/wazuh-control info | grep "WAZUH_VERSION"

# Review cluster status and node integrity
/var/ossec/bin/cluster_control -l

# Check for active connections to master node
netstat -an | grep 1516