A vulnerability was found in PAM. The secret information is stored in memory, where the attacker can trigger the victim program to execute by sending characters to its standard input (stdin). As this occurs, the attacker can train the branch predictor to execute an ROP chain speculatively. This flaw could result in leaked passwords, such as those found in /etc/shadow while performing authentications.

linux-pam (aka Linux PAM) before 1.6.0 allows attackers to cause a denial of service (blocked login process) via mkfifo because the openat call (for protect_dir) lacks O_DIRECTORY.

The Linux-PAM package before 1.5.2-6.1 for openSUSE Tumbleweed allows authentication bypass for SSH logins. The pam_access.so module doesn't correctly restrict login if a user tries to connect from an IP address that is not resolvable via DNS. In such conditions, a user with denied access to a machine can still get access. NOTE: the relevance of this issue is largely limited to openSUSE Tumbleweed and openSUSE Factory; it does not affect Linux-PAM upstream.

A flaw was found in Linux-Pam in versions prior to 1.5.1 in the way it handle empty passwords for non-existing users. When the user doesn't exist PAM try to authenticate with root and in the case of an empty password it successfully authenticate.

The _unix_run_helper_binary function in the pam_unix module in Linux-PAM (aka pam) before 1.2.1, when unable to directly access passwords, allows local users to enumerate usernames or cause a denial of service (hang) via a large password.

Multiple directory traversal vulnerabilities in pam_timestamp.c in the pam_timestamp module for Linux-PAM (aka pam) 1.1.8 allow local users to create arbitrary files or possibly bypass authentication via a .. (dot dot) in the (1) PAM_RUSER value to the get_ruser function or (2) PAM_TTY value to the check_tty function, which is used by the format_timestamp_name function.

The _expand_arg function in the pam_env module (modules/pam_env/pam_env.c) in Linux-PAM (aka pam) before 1.1.5 does not properly handle when environment variable expansion can overflow, which allows local users to cause a denial of service (CPU consumption).

Stack-based buffer overflow in the _assemble_line function in modules/pam_env/pam_env.c in Linux-PAM (aka pam) before 1.1.5 allows local users to cause a denial of service (crash) and possibly execute arbitrary code via a long string of white spaces at the beginning of the ~/.pam_environment file.

The pam_sm_close_session function in pam_xauth.c in the pam_xauth module in Linux-PAM (aka pam) 1.1.2 and earlier does not properly handle a failure to determine a certain target uid, which might allow local users to delete unintended files by executing a program that relies on the pam_xauth PAM check.

The pam_env module in Linux-PAM (aka pam) 1.1.2 and earlier reads the .pam_environment file in a user's home directory, which might allow local users to run programs with an unintended environment by executing a program that relies on the pam_env PAM check.