CVE-2026-26204Public exploit

Service crash via empty-filename buffer underwrite

Published Apr 29, 2026 · Updated Apr 29, 2026

Heap buffer underwrite in Wazuh 1.0.0 through 4.14.3 allows local users with alert-log access to crash wazuh-logcollector. GetAlertData subtracts one from the unsigned length of an empty duplicated filename, wraps the index, and writes a null byte immediately before the heap buffer. Exploitation requires an ossecalert-formatted monitored log and a crafted syscheck alert containing an empty filename; the demonstrated consequence is service interruption through heap corruption.

CVSS severity4.4
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer underwrite in Wazuh 1.0.0 through 4.14.3 allows local users with alert-log access to crash wazuh-logcollector. GetAlertData subtracts one from the unsigned length of an empty duplicated filename, wraps the index, and writes a null byte immediately before the heap buffer. Exploitation requires an ossecalert-formatted monitored log and a crafted syscheck alert containing an empty filename; the demonstrated consequence is service interruption through heap corruption.

The record

CVE
CVE-2026-26204
Published
Apr 29, 2026
Updated
Apr 29, 2026
Vendor
Wazuh
Product
Wazuh
Classifications
CWE-124, CWE-191
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.0.0, < 4.14.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Wazuh · Wazuhversion=>= 1.0.0, < 4.14.4

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.4GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-124Buffer Underwrite ('Buffer Underflow')
CWE-191Integer Underflow (Wrap or Wraparound)

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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