What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-18 · updated 2026-09-24
• Weakness: CWE-674

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.

Affected products

• icinga2: before 2.14.9; from 2.15.0, < 2.15.4; from 2.16.0, < 2.16.2

References

• https://github.com/Icinga/icinga2/commit/391504eaa9ed9aee81f84008c57ec821974b74ee
• https://github.com/Icinga/icinga2/commit/3d9166ff52ff1a64a286c39af57957d63442c137
• https://github.com/Icinga/icinga2/commit/4964d2444ca5c4fae9036054554e1c6e0025fb89
• https://github.com/Icinga/icinga2/commit/ed163a8aa9d296820dd2ad14c47bf3f6a3fcce7d
• https://github.com/Icinga/icinga2/pull/10908
• https://github.com/Icinga/icinga2/releases/tag/v2.14.9
• https://github.com/Icinga/icinga2/releases/tag/v2.15.4
• https://github.com/Icinga/icinga2/releases/tag/v2.16.2
• https://github.com/Icinga/icinga2/security/advisories/GHSA-wh38-wg57-5w7g
• https://icinga.com/blog/icinga2-security-release-v2-16-2

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