general/login.php in phpCollab 2.5 rc3 and earlier allows remote attackers to execute arbitrary commands via shell metacharacters in unspecified input related to the SSL_CLIENT_CERT environment variable. NOTE: in some environments, SSL_CLIENT_CERT always has a base64-encoded string value, which may impose constraints on injection for typical shells.
https://exchange.xforce.ibmcloud.com/vulnerabilities/47522
http://www.securityfocus.com/bid/32964
http://security.gentoo.org/glsa/glsa-200812-20.xml