CVE-2026-40106: wazuh Heap Overflow — Exploit & Fix

Description

Wazuh is a free and open source platform used for threat prevention, detection, and response. Versions 4.6.0 and above prior to 4.14.5 contain a heap-based buffer overflow vulnerability in the syscheck component of the Wazuh agent for Windows. When expanding registry paths containing wildcards (* or ?), the agent allocates a fixed-size heap buffer of 256 bytes (OS_SIZE_256). By creating a registry subkey with a maximum allowed length (255 characters) inside a monitored path, a low-privileged local attacker can force an out-of-bounds write during string concatenation. Since wazuh-agent.exe runs as NT AUTHORITY\SYSTEM, this can lead to a silent Denial of Service (blinding the agent) or potentially Local Privilege Escalation (LPE). This issue has been fixed in version 4.14.5.

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CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0010

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-122 CWE-122

Affected Products

Vendor	Product	Versions
wazuh	wazuh	4.6.0 — 4.14.5

References

Advisories & Patches

https://github.com/wazuh/wazuh/security/advisories/GHSA-qvrc-pcfc-jhqc https://github.com/wazuh/wazuh/security/advisories/GHSA-qvrc-pcfc-jhqc

Exploits

https://github.com/wazuh/wazuh/security/advisories/GHSA-qvrc-pcfc-jhqc https://github.com/wazuh/wazuh/security/advisories/GHSA-qvrc-pcfc-jhqc

Frequently Asked Questions

What is CVE-2026-40106? +

Wazuh is a free and open source platform used for threat prevention, detection, and response. Versions 4.6.0 and above prior to 4.14.5 contain a heap-based buffer overflow vulnerability in the syscheck component of the Wazuh agent for Windows. When expanding registry paths containing wildcards (* or ?), the agent allocates a fixed-size heap buffer of 256 bytes (OS_SIZE_256). By creating a registry subkey with a maximum allowed length (255 characters) inside a monitored path, a low-privileged local attacker can force an out-of-bounds write during string concatenation. Since wazuh-agent.exe runs as NT AUTHORITY\SYSTEM, this can lead to a silent Denial of Service (blinding the agent) or potentially Local Privilege Escalation (LPE). This issue has been fixed in version 4.14.5. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2026-40106? +

CVE-2026-40106 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0010, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40106? +

CVE-2026-40106 affects products from wazuh, specifically: wazuh. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40106? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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