WordPress 1.5.2 is vulnerable and you should upgrade.
However, I didn’t want to upgrade this blog to 2.x because I don’t have much need for the new “features” that 2.x offers and also I fear a lot of my plugins that I use here may break.
However, I did want my blog to be secure. Thanks to suggestions from Robert Deaton, I upgraded my blog to the latest 1.5.x release.
You cannot get this release directly from the WP site, so you will need to get it from the Trac.
I have written a guide for the same, so that you can get your blog secured.