CVE-2026-26204: Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-29 · updated 2026-06-17
Weakness: CWE-124

Description

Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.

Affected products

wazuh: from 1.0.0 before 4.14.4 — fixed in 4.14.4

How to fix

Upgrade to a fixed version: wazuh 4.14.4. Check the vendor advisory for mitigations.

References

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