Security fix: An SQL-injection security hole has been found in multi-byte encoding processing. The bug was in the server, incorrectly parsing the string escaped with the mysql_real_escape_string() C API function. (CVE-2006-2753, Bug#8378)

This vulnerability was discovered and reported by Josh Berkus <josh@postgresql.org> and Tom Lane <tgl@sss.pgh.pa.us> as part of the inter-project security collaboration of the OSDB consortium. For more information about SQL injection, please see the following text.

Discussion: An SQL-injection security hole has been found in multi-byte encoding processing. An SQL-injection security hole can include a situation whereby when a user supplied data to be inserted into a database, the user might inject SQL statements into the data that the server will execute. With regards to this vulnerability, when character set unaware-escaping is used (for example, addslashes() in PHP), it is possible to bypass the escaping in some multi-byte character sets (for example, SJIS, BIG5 and GBK). As a result, a function such as addslashes() is not able to prevent SQL-injection attacks. It is impossible to fix this on the server side. The best solution is for applications to use character set-aware escaping offered by a function such mysql_real_escape_string().

However, a bug was detected in how the MySQL server parses the output of mysql_real_escape_string(). As a result, even when the character set-aware function mysql_real_escape_string() was used, SQL injection was possible. This bug has been fixed.

Workarounds: If you are unable to upgrade MySQL to a version that includes the fix for the bug in mysql_real_escape_string() parsing, but run MySQL 5.0.1 or higher, you can use the NO_BACKSLASH_ESCAPES SQL mode as a workaround. (This mode was introduced in MySQL 5.0.1.) NO_BACKSLASH_ESCAPES enables an SQL standard compatibility mode, where backslash is not considered a special character. The result will be that queries will fail.

To set this mode for the current connection, enter the following SQL statement:

SET sql_mode='NO_BACKSLASH_ESCAPES';

You can also set the mode globally for all clients:

SET GLOBAL sql_mode='NO_BACKSLASH_ESCAPES';

This SQL mode also can be enabled automatically when the server starts by using the command-line option --sql-mode=NO_BACKSLASH_ESCAPES or by setting sql-mode=NO_BACKSLASH_ESCAPES in the server option file (for example, my.cnf or my.ini, depending on your system).

The dropping of a temporary table whose name contained a backtick ('`') character was not correctly written to the binary log, which also caused it not to be replicated correctly. (Bug#19188)

The patch for Bug#8303 broke the fix for Bug#8378 and was undone. (In string literals with an escape character (\) followed by a multi-byte character that has a second byte of (\), the literal was not interpreted correctly. The next byte now is escaped, not the entire multi-byte character. This means it a strict reverse of the mysql_real_escape_string() function.)

The client libraries had not been compiled for position-indpendent code on Solaris-SPARC and AMD x86_64 platforms. (Bug#13159, Bug#14202, Bug#18091)

Running myisampack followed by myisamchk with the --unpack option would corrupt the auto_increment key. (Bug#12633)