The calling logic for WhatsApp for Android prior to v2.21.23, WhatsApp Business for Android prior to v2.21.23, WhatsApp for iOS prior to v2.21.230, WhatsApp Business for iOS prior to v2.21.230, WhatsApp for KaiOS prior to v2.2143, WhatsApp Desktop prior to v2.2146 could have allowed an out-of-bounds write if a user makes a 1:1 call to a malicious actor.