CVE 2013-4313

Moodle through 2.2.11, 2.3.x before 2.3.9, 2.4.x before 2.4.6, and 2.5.x before 2.5.2 does not prevent use of '\0' characters in query strings, which might allow remote attackers to conduct SQL injection attacks against Microsoft SQL Server via a crafted string.

See the CVE page on Mitre.org for more details.