The mysql command-line client does not quote HTML special characters like < in its output. This allows an attacker who is able to write data into a table to hide or modify records in the output, and to inject potentially dangerous code, e. g. Javascript to perform cross-site scripting or cross-site request forgery attacks.
$ mysql --html --execute "select '<a>'" ...
<TABLE BORDER=1><TR><TH><a></TH></TR><TR><TD><a></TD></TR></TABLE>
All.
Users are advised to install the available patch from http://bugs.mysql.com/bug.php?id=27884.
If another resolution is not feasible, users are advised to modify their SELECT statements to filter out the characters < and &:
SELECT REPLACE(REPLACE(...,'&','&'),'<','<') AS ...;
This workaround is incompatible with the described resolution and should be reversed after installation of the patch.
2007-04-17 Opened bug on mysql.com
2008-05-01 Patch available
The bug is filed on http://bugs.mysql.com/bug.php?id=27884.
This advisory is available from https://henlich.de/it-security/mysql-command-line-client-html-injection-vulnerability/.