Star before 1.5_alpha46 does not drop the effective user ID (euid) before calling external programs, which could allow local users to gain privileges by modifying the RSH environment variable to reference a malicious program.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17297
http://www.securityfocus.com/bid/11141
http://www.kb.cert.org/vuls/id/339089