7.5 - USN-303-1

A security issue affects the following Ubuntu releases:

Ubuntu 5.10 Ubuntu 6.06 LTS

This advisory also applies to the corresponding versions of Kubuntu, Edubuntu, and Xubuntu.

The problem can be corrected by upgrading your system to the following package versions:

Ubuntu 5.10:
libmysqlclient14 4.1.12-1ubuntu3.5
mysql-server-4.1 4.1.12-1ubuntu3.5

Ubuntu 6.06 LTS:
libmysqlclient15off 5.0.22-0ubuntu6.06
mysql-server-5.0 5.0.22-0ubuntu6.06

In general, a standard system upgrade is sufficient to effect the necessary changes.

Details follow:

An SQL injection vulnerability has been discovered when using less popular multibyte encodings (such as SJIS, or BIG5) which contain valid multibyte characters that end with the byte 0x5c (the representation of the backslash character >>\<< in ASCII).

Many client libraries and applications use the non-standard, but popular way of escaping the >>'<< character by replacing all occurences of it with >>\'<<. If a client application uses one of the affected encodings and does not interpret multibyte characters, and an attacker supplies a specially crafted byte sequence as an input string parameter, this escaping method would then produce a validly-encoded character and an excess >>'<< character which would end the string. All subsequent characters would then be interpreted as SQL code, so the attacker could execute arbitrary SQL commands.

The updated packages fix the mysql_real_escape_string() function to escape quote characters in a safe way. If you use third-party software which uses an ad-hoc method of string escaping, you should convert them to use mysql_real_escape_string() instead, or at least use the standard SQL method of escaping >>'<< with >>''<<.