Icinga 2 is a monitoring system which checks the availability of network resources, notifies users of outages, and generates performance data for reporting. Prior to versions 2.12.12, 2.13.12, and 2.14.6, the VerifyCertificate() function can be tricked into incorrectly treating certificates as valid. This allows an attacker to send a malicious certificate request that is then treated as a renewal of an already existing certificate, resulting in the attacker obtaining a valid certificate that can be used to impersonate trusted nodes. This only occurs when Icinga 2 is built with OpenSSL older than version 1.1.0. This issue has been patched in versions 2.12.12, 2.13.12, and 2.14.6.

Icinga is a monitoring system which checks the availability of network resources, notifies users of outages, and generates performance data for reporting. The TLS certificate validation in all Icinga 2 versions starting from 2.4.0 was flawed, allowing an attacker to impersonate both trusted cluster nodes as well as any API users that use TLS client certificates for authentication (ApiUser objects with the clientcn attribute set). This vulnerability has been fixed in v2.14.3, v2.13.10, v2.12.11, and v2.11.12.