L2/07-415 Source: Mark Davis Date: 2007-12-06 Subject: Security issue in C7 Please add the following to the registry and agenda: C7 reads: C7. When a process purports not to modify the interpretation of a valid coded character sequence, it shall make no change to that coded character sequence other than the possible replacement of character sequences by their canonical-equivalent sequences or the deletion of noncharacter code points. Whenever a character is invisibly deleted (instead of replaced), it may cause a security problem. The issue is the following: A gateway might be checking for a sensitive sequence of characters, say "delete". If what is passed in is "deXlete", the gateway doesn't see it. But then if an internal process invisibly deletes the X, there can be a security breach when "delete" is then passed on further. -- Mark