Fcgboy

A use-after-free issue exists where a file descriptor can be closed while a thread is blocked in a `poll(2)` or `select(2)` call waiting for that descriptor. Since the blocked thread does not hold a reference to the underlying object, the object may be freed while the thread remains blocked. The kernel fails to unlink blocked threads from the per-object wait queue for certain file descriptor types before freeing the object. Consequently, when the blocked thread wakes up, it accesses memory that has already been freed. This can be triggered by an unprivileged local user to obtain superuser privileges.

A code injection vulnerability exists in the Ambari Alert Definition feature, allowing authenticated users to inject and execute arbitrary shell commands. The vulnerability arises when defining alert scripts, where the script filename field is executed using `sh -c`. An attacker with authenticated access can exploit this vulnerability to inject malicious commands, leading to remote code execution on the server.

A malicious user who has access to the Skipper server API can use a crafted upload request to write an arbitrary file to any location on the file system, which could lead to compromising the server. The issue is related to incorrect management of code generation. Exploitation of the issue may allow a remote attacker to write a file to any directory on the system using a specially formed API request.