Directory traversal vulnerability in upgrade.php in Piwigo before 2.3.4 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the language parameter.
https://www.htbridge.com/advisory/HTB23085
https://exchange.xforce.ibmcloud.com/vulnerabilities/75185
http://secunia.com/advisories/48903
http://piwigo.org/releases/2.3.4