CVE-2026-59786 Active agent heartbeat missing TLS check
Attackers can bypass TLS authentication to report arbitrary hosts as available, compromising data integrity in Zabbix Server and Proxy.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-59786?
CVE-2026-59786 is a medium-severity missing authorization vulnerability in Zabbix, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Zabbix Server and Proxy accept the active agent heartbeat message regardless of the configured PSK or certificate authentication. This means someone with access to the Zabbix trapper port can report an arbitrary host using an active agent as available, resulting in a loss of integrity.
Weakness: CWE-940
Which versions are affected by CVE-2026-59786?
How do I fix CVE-2026-59786?
Apply the vendor's patch.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-59786 being exploited?
There is no known exploitation of CVE-2026-59786 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-59786, GHSA-jmxh-h64m-45qp, UBUNTU-CVE-2026-59786.