CVE-2026-61551 Icinga 2: Stack overflow via deeply nested JSON objects
Remote attackers can crash the Icinga 2 service by sending deeply nested JSON objects, causing a stack overflow and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61551?
CVE-2026-61551 is a high-severity denial of service vulnerability in icinga2, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Icinga 2 is an open source monitoring system. Prior to 2.14.9, 2.15.4, and 2.16.2, parsing deeply nested JSON can exhaust the call stack because nesting depth is not bounded. The affected JSON parsing paths are reachable by unauthenticated network clients through the Icinga 2 service on TCP port 5665, allowing a remote attacker to crash the process, while possible code execution has not been demonstrated. This issue is fixed in versions 2.14.9, 2.15.4, and 2.16.2.
Weakness: CWE-674
Which versions are affected by CVE-2026-61551?
How do I fix CVE-2026-61551?
Upgrade to a fixed version.
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-2026-61551 being exploited?
There is no known exploitation of CVE-2026-61551 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-61551, GHSA-wh38-wg57-5w7g, UBUNTU-CVE-2026-61551.