Effekseer consists of a particle effect editing tool and a runtime to play back the effects. Effekseer runtime is expected to be embedded in the applications such as games and 3D CG viewers. Effekseer improperly validates input data ("effect file"), which may cause out-of-bounds read.<a href='https://cwe.mitre.org/data/definitions/237.html' target='_blank'></a><ul><li>Improper handling of structural elements (CWE-237) - CVE-2026-120386</li></ul>Yukimura Aneha reported this vulnerability to IPA. JPCERT/CC coordinated with the developer under Information Security Early Warning Partnership.