GeoGebra Classic version 5.0.631.0-d contains a denial of service vulnerability that allows attackers to crash the application through buffer overflow attacks. The vulnerability is exploited by generating a large buffer containing 800,000 repeated characters and pasting it into the 'Entrada:' input field. This causes the application to crash due to inability to handle oversized buffer content. The vulnerability has been assigned CVE-2021-47876 and has exploit code publicly available. The attack vector is local and requires user interaction to paste the malicious content.