Yesterday visitors to my blog, including me, discovered that we were unable to leave comments. I also discovered that I was unable to execute any administrative functions. We were greeted with the following message:
We’re sorry, but we could not fulfill your request for /wp-comments-post.php on this server.
Your Internet Protocol address is listed on a blacklist of addresses involved in malicious or illegal activity. See the listing below for more details on specific blacklists and removal procedures.
I did not have any idea of where this block was coming from, so I contacted my web hosting company to see if they knew anything. After checking the server, they reported that it was fine and that the problem came from my WordPress installation. So, I began checking my plugins’ web pages for updates, starting at the top with Bad Behaviour. What do you know? Bad Behaviour was the culprit:
All users should update to Bad Behavior 2.0.11 immediately to prevent being blocked from your own site.
Within the past two days users have found themselves blocked from their own sites while using recent versions of Bad Behavior. A third party blacklist which Bad Behavior queries recently began sending false positives for any IP address queried, causing everyone using Bad Behavior to be blocked. This issue is fixed in Bad Behavior 2.0.11.
After updating the Bad Behaviour plugin, everything is fine.