/var/logs 106MB

Hi friends,
on my Gallery3 installation, the directory /var/logs occupies 106MB,
in the directory many logs, with the same text:

2014-06-26 00:30:10 +02:00 --- error: Kohana_Exception [ 403 ]: @todo FORBIDDEN
/home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/gallery/helpers/access.php [ 202 ]
#0 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/gallery/helpers/access.php(425): access_Core::forbidden()
#1 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/gallery/libraries/MY_Forge.php(42): access_Core::verify_csrf()
#2 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/forge/libraries/Forge.php(164): Forge->validate()
#3 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/gallery/libraries/MY_Forge.php(41): Forge_Core->validate()
#4 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/modules/comment/controllers/comments.php(33): Forge->validate()
#5 [internal function]: Comments_Controller->create('122')
#6 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/system/core/Kohana.php(331): ReflectionMethod->invokeArgs(Object(Comments_Controller), Array)
#7 [internal function]: Kohana_Core::instance(NULL)
#8 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/system/core/Event.php(208): call_user_func_array(Array, Array)
#9 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/application/Bootstrap.php(67): Event_Core::run('system.execute')
#10 /home/w53775/domains/pergraziaricevuta.it/public_html/gallery3/index.php(103): require('/home/w53775/do...')
#11 {main}
2014-06-26 00:30:10 +02:00 --- error: Missing messages entry kohana/core.errors.403 for message kohana/core

How could prevent? And what does this error mean?

many many thanks!
Davide
Italy