Let's break this down, first of all have a look at the CVSS score:
(AV:L/AC:M/Au:N/C:C/I:C/A:C) So:
- Access Vector: Local
- Access complexity: Medium
- Authentication: None
- Confidentiality: Complete
- Integrity: Complete
- Availability: Complete
The vulnerability can result in privilege escalation, meaning a user with few privileges, might gain access to the root account. However the current exploit, which is readily available only results in a Denial of Service. If someone is able to port this exploit, (maybe it already has but is not public yet) . Then there is a risk that someone could have used it. On the other hand, you should never allow people onto your machine if you don't trust them.So if you say that you trust your friends, then this shouldn't be an issue,but this does NOT mean you shouldn't patch the vulnerability!