[xss] a xss on "threadid" parameter in BBSMAX

i found a xss on "threadid" parameter in "post.aspx" in BBSMAX , it's "post.aspx?action=reply&threadid="

Vulnerable: BBSMAX 4.2 BBSMAX 4.1 BBSMAX 3.0

For example:
http://bbs.example.com/forum1/post.aspx?action=reply&threadid="><script>alert(/liscker/);</script>

BBSMAX Home Page : http://www.bbsmax.com/

BBSMAX is prone to an cross-site scripting vulnerability because the application fails to properly
sanitize user-supplied input. An attacker may leverage this issue to execute arbitrary script code in the
browser of an unsuspecting user in the context of the affected site. This may allow the attacker to steal
cookie-based authentication credentials and to launch other attacks.

The three versions of BBSMAX is vulnerable; other versions may also be affected.

Liscker

2010.3.10