admin_loader.php in PunBB 1.2.1 allows remote attackers to read arbitrary files via the plugin parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/19478
http://www.punbb.org/download/patch/punbb-1.2.1_to_1.2.2.patch
http://www.punbb.org/changelogs/1.2.1_to_1.2.2.txt