CVE-2026-71540 Wazuh Manager cluster header parsing allows pre-authentication memory exhaustion
Unauthenticated attackers can exhaust memory in Wazuh Manager by sending crafted cluster headers, causing service disruption.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-71540?
CVE-2026-71540 is a high-severity denial of service vulnerability in wazuh, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-71540?
How do I fix CVE-2026-71540?
No fix has been published for CVE-2026-71540 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-71540 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-71540 exists.
Sources
Also known as GHSA-78wx-4r6w-w73f.