CMS Made Simple Forums

In an old website, formbuilder has stopped working, giving a 403 error when submitting the form.

Someone can help me?

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Cms Version: 1.11.9
Installed Modules:
CGExtensions: 1.45
CMSMailer: 5.2.14
CMSPrinting: 1.0.5
FileManager: 1.4.3
Gallery: 2.0.3
JQueryTools: 1.2.6
ListIt2: 1.4.1
ListIt2modulimenu: 1.4.1
MenuManager: 1.8.6
MicroTiny: 1.2.5
MleCMS: 1.11.4
ModuleManager: 1.5.5
News: 2.14.1
SEOTools2: 1.2.1
CGContentUtils: 1.4.3
Search: 1.7.11
ThemeManager: 1.1.8
TinyMCE: 2.9.12
btAdminer: 1.7.1
FormBuilder: 0.8.1.3
CGSimpleSmarty: 1.7.4
CGJobMgr: 1.3.3
NMS: 2.9.2
UsersGuide: 1.8.1
Cron: 0.0.8

Config Information:
php_memory_limit:
process_whole_template:
max_upload_size: 40000000
url_rewriting: mod_rewrite
page_extension: .html
query_var: page
image_manipulation_prog: GD
auto_alias_content: true
locale:
default_encoding: utf-8
admin_encoding: utf-8
set_names: true

Php Information:
phpversion: 5.4.45-0+deb7u10
md5_function: On (Vero)
gd_version: 2
tempnam_function: On (Vero)
magic_quotes_runtime: Off (Falso)
E_STRICT: 0
E_DEPRECATED: 0
memory_limit: 128M
max_execution_time: 60
output_buffering: 8192
safe_mode: Off (Falso)
file_uploads: On (Vero)
post_max_size: 40M
upload_max_filesize: 40M
session_save_path: Nessun controllo perchè open basedir è attivo
session_use_cookies: On (Vero)
xml_function: On (Vero)
xmlreader_class: On (Vero)

Server Information:
Server Api: apache2handler
Server Db Type: MySQL (mysqli)
Server Db Version: 5.5.57
Server Db Grants: Ho trovato una dichiarazione "GRANT ALL" che sembra essere adatta
Server Time Diff: Nessuna differenza di orario del filesystem individuata

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A URL would probably help here if you can post it.

And your CMSMS is out of date:
https://docs.cmsmadesimple.org/upgrading/to-cmsms-2.x

This is a production website, so I had to disable the forms.
The thing is the forms were working until today...

https://en.wikipedia.org/wiki/HTTP_403

You really should check the server logs or ask your hosting provider.
Could be the server configuration changed (e.g. not allowing older phpmailer which MIGHT be included in this (too old) version of CMSMS).