CVE-2026-44254 in Wazuh
Summary
by MITRE • 08/19/2026
Wazuh is a free and open source platform used for threat prevention, detection, and response. From 1.0.0 until 4.14.6 and 5.0.0-beta2, HandleSecureMessage() in src/remoted/secure.c passes a pointer inside its stack buffer to ReadSecMSG(), and src/os_crypto/shared/msgs.c decompresses up to OS_MAXSTR bytes at that offset. For an encrypted agent message on TCP port 1514 that expands to 65,536 bytes, os_zlib_uncompress() writes a terminating null byte beyond the end of the destination buffer. The resulting stack out-of-bounds write in the root-level remoted daemon can crash message processing and disrupt agent communications. This issue is fixed in versions 4.14.6 and 5.0.0-beta2.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified as a critical flaw within the Wazuh platform, specifically affecting versions from 1.0.0 through 4.14.6 and version 5.0.0-beta2, centers on improper memory management in the secure message handling subsystem. This issue resides primarily in the HandleSecureMessage function located in src/remoted/secure.c, which is part of the remoted daemon responsible for processing incoming agent communications over TCP port 1514. The core technical flaw involves a stack-based buffer overflow that occurs during the decompression and validation of encrypted messages received from agents. When an agent sends an encrypted message to the Wazuh server, the system attempts to decrypt and process it using specific cryptographic libraries. During this process, HandleSecureMessage passes a pointer derived from its local stack buffer to ReadSecMSG for further processing. This design choice creates a dangerous dependency on the integrity of the source buffer relative to the destination operations performed by downstream functions.
The critical failure point occurs within src/os_crypto/shared/msgs.c when the system attempts to decompress the incoming data using os_zlib_uncompress(). The function is configured to handle up to OS_MAXSTR bytes, which represents a predefined maximum string length limit intended to prevent excessive memory allocation. However, under specific conditions where an encrypted agent message expands significantly during decryption and decompression—specifically reaching or exceeding 65,536 bytes—the operation exceeds the bounds of the allocated stack buffer. The zlib library's uncompression routine writes data into a destination buffer that is insufficiently sized to accommodate the expanded payload. Crucially, after copying the uncompressed content, os_zlib_uncompress() appends a terminating null byte to ensure string termination in C-style strings. This final write operation places a single byte beyond the end of the allocated stack memory region, resulting in an out-of-bounds write.
This specific type of vulnerability is classified under CWE-121, which denotes a Stack-based Buffer Overflow. The exploitation vector for this flaw allows for potential denial of service and potentially remote code execution depending on the exact layout of the stack at runtime. Because the remoted daemon operates with root-level privileges to facilitate comprehensive threat detection and response capabilities, any compromise or crash in this process has severe operational implications. A successful trigger of this vulnerability can cause immediate termination of the message processing thread within the remoted service. This disruption leads to a breakdown in communication between Wazuh agents and the central manager, effectively blinding the security operations center to events originating from those affected agents. In high-availability environments, such crashes can lead to cascading failures if not properly isolated by supervisor processes, thereby reducing the overall resilience of the intrusion detection system.
From an offensive perspective, this vulnerability aligns with MITRE ATT&CK technique T1498, Network Denial of Service, as it allows an attacker to disrupt service availability through resource exhaustion or process termination. Furthermore, if the stack layout permits control over return addresses or function pointers adjacent to the overflowed buffer, it could theoretically be leveraged for arbitrary code execution, mapping towards techniques such as T1059 Command and Scripting Interpreter via exploitation of binary vulnerabilities. The impact is particularly acute because TCP port 1514 is often exposed in network architectures designed for agent-to-server communication, potentially making this attack surface accessible to external adversaries if firewall rules are not strictly enforced between agents and managers.
Mitigation strategies must prioritize immediate patching as the primary defense vector. Organizations running affected versions of Wazuh should upgrade immediately to version 4.14.6 or later, including any subsequent releases in the 5.x branch that have addressed this memory management error. The fix involves correcting the buffer allocation logic and ensuring that decompression operations respect strict boundary checks before writing terminating characters. In environments where immediate patching is not feasible due to operational constraints, network segmentation should be enforced to restrict access to TCP port 1514 exclusively to trusted agent IP addresses. Additionally, deploying intrusion prevention systems capable of detecting anomalous packet sizes or malformed TLS handshakes associated with this exploit can provide a layer of defense in depth. Regular auditing of Wazuh configurations and monitoring for unexpected remoted daemon restarts serve as effective detection mechanisms for potential exploitation attempts.