Buffer overflow in ICQ 99b 1.1.1.1 client allows remote attackers to execute commands via a malformed URL within an ICQ message.

ICQ99 ICQ web server build 1701 with "Active Homepage" enabled generates allows remote attackers to determine the existence of files on the server by comparing server responses when a file exists ("404 Forbidden") versus when a file does not exist ("404 not found").

The ICQ Webserver allows remote attackers to use .. to access arbitrary files outside of the user's personal directory.

Win32 ICQ 98a 1.30, and possibly other versions, does not display the entire portion of long filenames, which could allow attackers to send an executable file with a long name that contains so many spaces that the .exe extension is not displayed, which could make the user believe that the file is safe to open from the client.

ICQ 98 beta on Windows NT leaks the internal IP address of a client in the TCP data segment of an ICQ packet instead of the public address (e.g. through NAT), which provides remote attackers with potentially sensitive information about the client or the internal network configuration.