admin/plugin.php in Piwigo through 2.8.3 doesn't validate the sections variable while using it to include files. This can cause information disclosure and code execution if it contains a .. sequence.
https://github.com/Piwigo/Piwigo/issues/574#issuecomment-267938358
https://github.com/Piwigo/Piwigo/commit/9004fdfc0b4a11cb32e9e15a5f67e4ec827e82dc
https://github.com/Piwigo/Piwigo/commit/8796e43aa344681d92a92e1f9b985409d4f36e31