systemd before 247 does not adequately block local privilege escalation for some Sudo configurations, e.g., plausible sudoers files in which the "systemctl status" command may be executed. Specifically, systemd does not set LESSSECURE to 1, and thus other programs may be launched from the less program. This presents a substantial security risk when running systemctl from Sudo, because less executes as root when the terminal size is too small to show the complete systemctl output.

An off-by-one Error issue was discovered in Systemd in format_timespan() function of time-util.c. An attacker could supply specific values for time and accuracy that leads to buffer overrun in format_timespan(), leading to a Denial of Service.

A use-after-free vulnerability was found in systemd. This issue occurs due to the on_stream_io() function and dns_stream_complete() function in 'resolved-dns-stream.c' not incrementing the reference counting for the DnsStream object. Therefore, other functions and callbacks called can dereference the DNSStream object, causing the use-after-free when the reference is still used later.

A flaw was found in systemd. An uncontrolled recursion in systemd-tmpfiles may lead to a denial of service at boot time when too many nested directories are created in /tmp.

basic/unit-name.c in systemd prior to 246.15, 247.8, 248.5, and 249.1 has a Memory Allocation with an Excessive Size Value (involving strdupa and alloca for a pathname controlled by a local attacker) that results in an operating system crash.

systemd through v245 mishandles numerical usernames such as ones composed of decimal digits or 0x followed by hex digits, as demonstrated by use of root privileges when privileges of the 0x0 user account were intended. NOTE: this issue exists because of an incomplete fix for CVE-2017-1000082.

A heap use-after-free vulnerability was found in systemd before version v245-rc1, where asynchronous Polkit queries are performed while handling dbus messages. A local unprivileged attacker can abuse this flaw to crash systemd services or potentially execute code and elevate their privileges, by sending specially crafted dbus messages.

An issue was discovered in button_open in login/logind-button.c in systemd before 243. When executing the udevadm trigger command, a memory leak may occur.

systemd 239 through 245 accepts any certificate signed by a trusted certificate authority for DNS Over TLS. Server Name Indication (SNI) is not sent, and there is no hostname validation with the GnuTLS backend. NOTE: This has been disputed by the developer as not a vulnerability since hostname validation does not have anything to do with this issue (i.e. there is no hostname to be sent)

In systemd 240, bus_open_system_watch_bind_with_description in shared/bus-util.c (as used by systemd-resolved to connect to the system D-Bus instance), calls sd_bus_set_trusted, which disables access controls for incoming D-Bus messages. An unprivileged user can exploit this by executing D-Bus methods that should be restricted to privileged users, in order to change the system's DNS resolver settings.

It was discovered that a systemd service that uses DynamicUser property can get new privileges through the execution of SUID binaries, which would allow to create binaries owned by the service transient group with the setgid bit set. A local attacker may use this flaw to access resources that will be owned by a potentially different service in the future, when the GID will be recycled.

It was discovered that a systemd service that uses DynamicUser property can create a SUID/SGID binary that would be allowed to run as the transient service UID/GID even after the service is terminated. A local attacker may use this flaw to access resources that will be owned by a potentially different service in the future, when the UID/GID will be recycled.

In systemd before v242-rc4, it was discovered that pam_systemd does not properly sanitize the environment before using the XDG_SEAT variable. It is possible for an attacker, in some particular configurations, to set a XDG_SEAT environment variable which allows for commands to be checked against polkit policies using the "allow_active" element rather than "allow_any".

An allocation of memory without limits, that could result in the stack clashing with another memory region, was discovered in systemd-journald when many entries are sent to the journal socket. A local attacker, or a remote one if systemd-journal-remote is used, may use this flaw to crash systemd-journald or execute code with journald privileges. Versions through v240 are vulnerable.

An allocation of memory without limits, that could result in the stack clashing with another memory region, was discovered in systemd-journald when a program with long command line arguments calls syslog. A local attacker may use this flaw to crash systemd-journald or escalate his privileges. Versions through v240 are vulnerable.