CVE-2018-9275
In check_user_token in util.c in the Yubico PAM module (aka pam_yubico) 2.18 through 2.25, successful logins can leak file descriptors to the auth mapping file, which can lead to information disclosure (serial number of a device) and/or DoS (reaching the maximum number of file descriptors).
Source: CVE-2018-9275