Piwigo version 12.2.0 is vulnerable to stored cross-site scripting (XSS), which can lead to privilege escalation. In this way, admin can steal webmaster's cookies to get the webmaster's access.
Piwigo is image gallery software written in PHP. When a criteria is not met on a host, piwigo defaults to usingmt_rand in order to generate password reset tokens. mt_rand output can be predicted after recovering the seed used to generate it. This low an unauthenticated attacker to take over an account providing they know an administrators email address in order to be able to request password reset.
show_default.php in the LocalFilesEditor extension before 11.4.0.1 for Piwigo allows Local File Inclusion because the file parameter is not validated with a proper regular-expression check.