Vulnerability in Icinga Icinga2

CVE-2026-61551

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H.

EPSS exploit prediction

EPSS: 0.009 (61.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 61.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-61551: held from 0.009 to 0.009.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

  • Icinga Icinga2 — versions < 2.14.9, >= 2.15.0, < 2.15.4, >= 2.16.0, < 2.16.2

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-61551?
CVE-2026-61551 is a high-severity vulnerability in Icinga Icinga2, classified under Uncontrolled Recursion. CVSS score: 8.6/10. Published 2026-09-18.
How severe is CVE-2026-61551?
High severity. CVSS v3 base score is 8.6 out of 10.