High severity · published Sep 24, 2026
CVE-2026-71540
Wazuh Manager cluster header parsing allows pre-authentication memory exhaustion
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
Wazuh is an open-source security platform providing unified XDR and SIEM protection for endpoints and cloud workloads. From 3.9.0 until 4.14.7, wazuh-clusterd in framework/wazuh/core/cluster/common.py allocates a payload buffer using the size declared in a 20-byte cluster protocol header before Fernet decryption validates the peer. An unauthenticated network peer can declare a payload of up to 256 MiB, stop sending after the header, and retain that allocation until the TCP connection closes. The cluster listener has no application-level per-source connection budget in affected versions, allowing concurrent sockets to multiply memory consumption and potentially terminate the cluster process, disrupt synchronization, and interrupt distributed API forwarding. This issue is fixed in version 4.14.7.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WA
wazuh · wazuh
>= 3.9.0, < 4.14.7 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-71540
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-71540
x_refsource_CONFIRM
https://github.com/wazuh/wazuh/security/advisories/GHSA-78wx-4r6w-w73f
x_refsource_MISC
https://github.com/wazuh/wazuh/pull/37280
x_refsource_MISC
https://github.com/wazuh/wazuh/commit/9a996bc23d28725f6c1f8f7808355d90e20d3382
x_refsource_MISC
https://github.com/wazuh/wazuh/releases/tag/v4.14.7
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