Heap-based buffer overflow the "Answering Service" function in ICQ 2003b Build 3916 allows local users to cause a denial of service (application crash) via a long string in the "AwayMsg Presets" value in the ICQ\ICQPro\DefaultPrefs\Presets registry key.

Heap-based buffer overflow in the MCRegEx__Search function in AOL ICQ Pro 2003b Build 3916 and earlier allows remote attackers to execute arbitrary code via an inconsistent length field of a Message in a 0x2711 Type-Length-Value (TLV) type.

ICQ Inc. (formerly Mirabilis) ICQ 2003a, 2003b, Lite 4.0, Lite 4.1, and possibly other Windows versions allows user-assisted remote attackers to hide malicious file extensions and bypass Windows security warnings via a filename that ends in an assumed-safe extension such as JPG, and possibly containing other modified properties such as company name, icon, and description, which could trick a user into executing arbitrary programs.

GUI display truncation vulnerability in ICQ Inc. (formerly Mirabilis) ICQ 2003a, 2003b, Lite 4.0, Lite 4.1, and possibly other Windows versions allows user-assisted remote attackers to hide malicious file extensions, bypass Windows security warnings via a filename that is all uppercase and of a specific length, which truncates the malicious extension from the display and could trick a user into executing arbitrary programs.