source: https://www.securityfocus.com/bid/21843/info

Simplog is prone to an SQL-injection vulnerability because the application fails to properly sanitize user-supplied input before using it in an SQL query. 

A successful exploit could allow an attacker to compromise the application, access or modify data, or exploit vulnerabilities in the underlying database implementation.

This issue affects version 0.9.3.2; other versions may also be vulnerable.

NOTE: This issue was previously discussed in BID 17652 (Simplog Multiple SQL Injection Vulnerabilities) and an upgrade is available from the vendor. However, new reports indicate the latest version of the application is still vulnerable to this issue.

http://example.com/simplog/archive.php?blogid=1&pid=1111%20union%20select%201,1,1,login,1,password,1,1%20from%20blog_users%20where%20admin=1