An unsafe reflection flaw allows a user to supply a model definition that specifies arbitrary Java classes, enabling those classes to be loaded and executed by Apache Calcite. This vulnerability, classified as CWE‑470, can compromise confidentiality, integrity, and availability by allowing execution of attacker‑chosen code within the Calcite process or any bundled services.

The flaw exists in Apache Calcite versions from 1.5.0 up through 1.41.x. Versions 1.42 and newer contain the vendor‑provided fix and are not affected.

The CVSS score is 6.5 and the EPSS score is <1%, and the vulnerability is not listed in the CISA KEV catalog. The attack requires the ability to supply or influence a model definition that the Calcite engine processes; for applications that expose user‑controlled models without validation, exploitation can be straightforward. Because no public exploits are reported, the probability of attack is uncertain, but the potential impact remains high due to the remote code execution capability.