The KEYS subsystem in the Linux kernel before 4.14.6 omitted an access-control check when adding a key to the current task's default request-key keyring via the request_key() system call, allowing a local user to use a sequence of crafted system calls to add keys to a keyring with only Search permission (not Write permission) to that keyring, related to construct_get_dest_keyring() in security/keys/request_key.c. https://nvd.nist.gov/vuln/detail/CVE-2017-17807
