CVE-2026-25772: Wazuh Buffer Overflow Vulnerability

CVE-2026-25772 Overview

A stack-based buffer overflow vulnerability exists in the Wazuh Database synchronization module (wdb_delta_event.c) affecting Wazuh versions 4.4.0 through 4.14.2. The vulnerability stems from SQL query construction logic that allows for an integer underflow when calculating the remaining buffer size. This occurs because the code incorrectly aggregates the return value of snprintf. When a specific database synchronization payload exceeds the size of the query buffer (2048 bytes), the size calculation wraps around to a massive integer, effectively removing bounds checking for subsequent writes. This allows an attacker to corrupt the stack, leading to a Denial of Service (DoS) or potentially Remote Code Execution (RCE).

Critical Impact

Stack corruption vulnerability in Wazuh's database synchronization module allows attackers to cause Denial of Service or potentially achieve Remote Code Execution through crafted payloads exceeding the 2048-byte query buffer limit.

Affected Products

• Wazuh versions 4.4.0 to 4.14.2
• Wazuh Database Synchronization Module (wdb_delta_event.c)
• All platforms running affected Wazuh versions

Discovery Timeline

• 2026-03-17 - CVE-2026-25772 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2026-25772

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The flaw exists in how the Wazuh Database synchronization module handles SQL query construction. The code uses snprintf to build queries but incorrectly tracks the remaining buffer space by aggregating return values without proper validation. When processing large database synchronization payloads, the buffer size calculation can underflow, causing the remaining size variable to wrap around to an extremely large positive integer. This effectively disables all bounds checking for subsequent write operations into the fixed 2048-byte query buffer.

The network-accessible nature of this vulnerability means that an authenticated attacker with high privileges can potentially exploit this remotely. The impact spans confidentiality, integrity, and availability, as successful exploitation can lead to stack corruption enabling either service disruption or arbitrary code execution.

Root Cause

The root cause is an integer underflow in the buffer size calculation within the SQL query construction logic of wdb_delta_event.c. The code incorrectly handles the return value of snprintf when aggregating the bytes written to the buffer. When the cumulative bytes written exceed the 2048-byte buffer size, instead of properly detecting an overflow condition, the remaining size calculation produces a wrapped-around value that bypasses subsequent boundary checks, allowing unbounded writes to the stack.

Attack Vector

An attacker with high privileges and network access to the Wazuh management infrastructure can craft a malicious database synchronization payload that exceeds 2048 bytes. When the Wazuh Database synchronization module processes this payload:

1. The SQL query construction begins populating the fixed-size buffer
2. The size tracking variable accumulates bytes written via snprintf
3. When the accumulated size exceeds the buffer capacity, integer underflow occurs
4. Subsequent writes bypass bounds checking due to the massive calculated "remaining" size
5. The attacker can then overwrite stack memory, corrupting return addresses or other critical data

This can result in service crashes (Denial of Service) or, if carefully crafted, potentially redirect execution flow for Remote Code Execution.

The vulnerability mechanism involves improper handling of snprintf return values during SQL query construction. When database synchronization payloads exceed 2048 bytes, the remaining buffer size calculation underflows, causing the check to wrap around and allow unbounded stack writes. For complete technical details, see the GitHub Security Advisory.

Detection Methods for CVE-2026-25772

Indicators of Compromise

• Unexpected crashes or service restarts of the Wazuh manager process
• Abnormally large database synchronization requests in Wazuh logs
• Memory corruption errors or segmentation faults in system logs related to Wazuh services
• Unusual network traffic patterns targeting Wazuh management ports

Detection Strategies

• Monitor Wazuh manager logs for database synchronization errors or crashes
• Implement network intrusion detection rules to identify oversized synchronization payloads
• Deploy SentinelOne Singularity platform to detect memory corruption exploitation attempts
• Set up process monitoring to alert on unexpected Wazuh service terminations

Monitoring Recommendations

• Enable detailed logging for the Wazuh Database synchronization module
• Monitor system memory usage and crash dumps for signs of buffer overflow exploitation
• Implement alerting for any anomalous database sync payload sizes approaching or exceeding 2048 bytes
• Review privileged user activity logs for suspicious synchronization operations

How to Mitigate CVE-2026-25772

Immediate Actions Required

• Upgrade to Wazuh version 4.14.3 or later immediately
• Review and restrict privileged access to Wazuh management infrastructure
• Monitor for any signs of exploitation attempts using the detection methods above
• Implement network segmentation to limit access to Wazuh management components

Patch Information

Wazuh has released version 4.14.3 which addresses this vulnerability. The fix properly handles the snprintf return value aggregation to prevent integer underflow during buffer size calculations. Organizations should upgrade to version 4.14.3 or later to remediate this vulnerability. Additional details are available in the Wazuh Security Advisory.

Workarounds

• Restrict network access to Wazuh management interfaces to trusted networks only
• Implement strict access controls limiting who can perform database synchronization operations
• Deploy additional monitoring and alerting for the Wazuh Database synchronization module
• Consider temporarily disabling or limiting database synchronization functionality if upgrade is not immediately possible

# Example: Restrict access to Wazuh management interface using firewall rules
# Allow only trusted management networks
iptables -A INPUT -p tcp --dport 1514 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 1515 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 1514 -j DROP
iptables -A INPUT -p tcp --dport 1515 -j DROP