CVE-2026-26204 Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData
A heap-based buffer underflow in Wazuh allows attackers to corrupt memory and cause denial of service or potential code execution via crafted alerts.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-26204?
CVE-2026-26204 is a medium-severity memory corruption vulnerability in Wazuh Wazuh, published on 29 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-26204?
It affects 1 product.
Products include Wazuh Wazuh.
How do I fix CVE-2026-26204?
No fix has been published for CVE-2026-26204 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-26204 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-26204 exists.
Other vulnerabilities in Wazuh Wazuh
- CVE-2025-24016 Wazuh Server Deserialization of Untrusted Data
- CVE-2024-32038 Wazuh Analysis Engine Event Decoder Heap-based Buffer Overflow Remote Code Execution Vulnerability
- CVE-2021-44079 Command injection in n/a
- CVE-2024-1243 Remote code execution and local privilege escalation in Wazuh Windows agent via NetNTLMv2 hash theft
- CVE-2026-61800 Wazuh cluster worker file sync allows arbitrary file write under /var/ossec (incomplete fix for CVE-2026-30893)
Sources
Also known as GHSA-j4c7-hwjw-8857.