app\modules\polygon\controllers\ProblemController in Jiangnan Online Judge (aka jnoj) 0.8.0 allows arbitrary file upload, as demonstrated by PHP code...

app\modules\polygon\controllers\ProblemController in Jiangnan Online Judge (aka jnoj) 0.8.0 allows arbitrary file upload, as demonstrated by PHP code (with a .php filename but the image/png content type) to the web/polygon/problem/tests URI.