CVE-2026-61551: Icinga 2: Stack overflow via deeply nested JSON objects

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.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

Low

Integrity

Low

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)0.9% · higher than 61% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

IC

icinga2 · Icinga

< 2.14.9; >= 2.15.0, < 2.15.4; >= 2.16.0, < 2.16.2 · source: vendor