I'm getting a 403 error when trying to save a post/draft on my wordpress site, but it only occurs with specific words like "in(", "is(" or "import".

I know that this doesn't seems to be posted on Server Fault forum, but when I asked this on the wordpress forum they said to me that I take to contact my server provider, and I did this. They said that nothing was wrong with the server, we have more websites with they and on any of these sites occur this error, I've heard about that this error could be a "mod_security" error, something like "Suspicious URL Filtering".

My server uses a CDN Cache server to improve its speed called GoCache CDN, its a Brazilian service (I'm from Brazil) and when I contacted my server provider, they said it couldn't be it because there wasn't any setting there about this and we have other sites with this same service (and wordpress too) that don't have this problem.

What I have already tested:

  • Downloaded the site and tested on a localhost and everything worked fine;
  • Uploaded on a different host (on the same server, but different url) and everything worked fine;
  • Accessed the same website in the same host and server but with a different url and everything worked fine (NOTE: that different url dont have the CDN service attached to it);

I don't really know what's happening with the server and/or the domain, I just need to know if anyone has something in mind about this.

NOTE: My server is Apache, and apparently the CDN Cache service has NGINX in its server.

NOTE 2: the main URL of the site is: http://revistapesca.com.br The second url (that's where everything works and dont have the CDN service): http://revistapescaesportiva.com.br


If everything works without the CDN, but fails with the CDN, it seems obvious that the CDN is the issue. Yes it does sound like some kind of security system is intercepting the requests. If it worked with and without the CDN I'd wonder if you had a suspect plugin causing problems.

Suggest you try a different CDN. The free tier of CloudFlare is probably good enough, it's what I use, or you can go up to their business plans for more features / service. There are many other CDNs, including the AWS CloudFront.

CloudFlare have a data centre in Sao Paulo as well as 100+ around the world, so even if your hosting is outside the country your static resources should load quickly.

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