Some of node links of content types are corrupted There are about 5000 nodes in my website of different content types. After a while (updating the Drupal to 7.34 and configuring the Server by server administrator) some of node links are corrupted and they are redirected to the front page. They are not too many but I don't know why some links that were working, are not working now. As an example the link /node/286 is redirected to the front page.

Is there any problem with the update that causes such thing?

The host server was victim of an attack and a few guest websites on it were hacked. So I guess (not sure!) the administrator may blocked some PHP functions, could this be the reason for such misbehavior of the links ? If it is right then why only a few of them are broken?
I've hit redirecting-to-front-page nodes in the past when I've stripped out use of the PHP filter input format. Turns out there was conditional logic that sometimes printed javascript redirect code.

Does the pages in question use the PHP filter format? If the admin blocked eval() perhaps it could stop execution of PHP and just render redirect code?

You can check disable_functions value in /admin/reports/status/php to confirm your suspicion about disabled functions.