There is a possible tty hijacking in shadow 4.x before 4.1.5 and sudo 1.x before 1.7.4 via "su - user -c program". The user session can be escaped to the parent session by using the TIOCSTI ioctl to push characters into the input buffer to be read by the next process.

References

• https://nvd.nist.gov/vuln/detail/CVE-2005-4890
• https://access.redhat.com/security/cve/cve-2005-4890
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2005-4890
• https://security-tracker.debian.org/tracker/CVE-2005-4890
• http://www.openwall.com/lists/oss-security/2012/11/06/8
• http://www.openwall.com/lists/oss-security/2013/05/20/3
• http://www.openwall.com/lists/oss-security/2013/11/28/10
• http://www.openwall.com/lists/oss-security/2013/11/29/5
• http://www.openwall.com/lists/oss-security/2014/10/20/9
• http://www.openwall.com/lists/oss-security/2014/10/21/1
• http://www.openwall.com/lists/oss-security/2014/12/15/5
• http://www.openwall.com/lists/oss-security/2016/02/25/6