systemd_project Vulnerabilities

A vulnerability was found in systemd-coredump. This flaw allows an attacker to force a SUID process to crash and replace it with a non-SUID binary to access the original's privileged process coredump, allowing the attacker to read sensitive data, such as /etc/shadow content, loaded by the original process. A SUID binary or process has a special type of permission, which allows the process to run with the file owner's permissions, regardless of the user executing the binary. This allows the process to access more restricted data than unprivileged users or processes would be able to. An attacker can leverage this flaw by forcing a SUID process to crash and force the Linux kernel to recycle the process PID before systemd-coredump can analyze the /proc/pid/auxv file. If the attacker wins the race condition, they gain access to the original's SUID process coredump file. They can read sensitive content loaded into memory by the original binary, affecting data confidentiality.

A vulnerability was found in systemd-resolved. This issue may allow systemd-resolved to accept records of DNSSEC-signed domains even when they have no signature, allowing man-in-the-middles (or the upstream DNS resolver) to manipulate records.

An issue was discovered in systemd 253. An attacker can modify the contents of past events in a sealed log file and then adjust the file such that checking the integrity shows no error, despite modifications. NOTE: the vendor reportedly sent "a reply denying that any of the finding was a security vulnerability."

An issue was discovered in systemd 253. An attacker can truncate a sealed log file and then resume log sealing such that checking the integrity shows no error, despite modifications. NOTE: the vendor reportedly sent "a reply denying that any of the finding was a security vulnerability."

An issue was discovered in systemd 253. An attacker can modify a sealed log file such that, in some views, not all existing and sealed log messages are displayed. NOTE: the vendor reportedly sent "a reply denying that any of the finding was a security vulnerability."

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.

A vulnerability was found in systemd. This security flaw can cause a local information leak due to systemd-coredump not respecting the fs.suid_dumpable kernel setting.

systemd 250 and 251 allows local users to achieve a systemd-coredump deadlock by triggering a crash that has a long backtrace. This occurs in parse_elf_object in shared/elf-util.c. The exploitation methodology is to crash a binary calling the same function recursively, and put it in a deeply nested directory to make its backtrace large enough to cause the deadlock. This must be done 16 times when MaxConnections=16 is set for the systemd/units/systemd-coredump.socket file.

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.

An exploitable denial-of-service vulnerability exists in Systemd 245. A specially crafted DHCP FORCERENEW packet can cause a server running the DHCP client to be vulnerable to a DHCP ACK spoofing attack. An attacker can forge a pair of FORCERENEW and DCHP ACK packets to reconfigure the server.

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.

systemd 37-1 does not properly handle non-existent services, which causes a denial of service (failure of login procedure).

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.

systemd 242 changes the VT1 mode upon a logout, which allows attackers to read cleartext passwords in certain circumstances, such as watching a shutdown, or using Ctrl-Alt-F1 and Ctrl-Alt-F2. This occurs because the KDGKBMODE (aka current keyboard mode) check is mishandled.

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 issue was discovered in sd-bus in systemd 239. bus_process_object() in libsystemd/sd-bus/bus-objects.c allocates a variable-length stack buffer for temporarily storing the object path of incoming D-Bus messages. An unprivileged local user can exploit this by sending a specially crafted message to PID1, causing the stack pointer to jump over the stack guard pages into an unmapped memory region and trigger a denial of service (systemd PID1 crash and kernel panic).

It was discovered systemd does not correctly check the content of PIDFile files before using it to kill processes. When a service is run from an unprivileged user (e.g. User field set in the service file), a local attacker who is able to write to the PIDFile of the mentioned service may use this flaw to trick systemd into killing other services and/or privileged processes. Versions before v237 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 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.

An out of bounds read was discovered in systemd-journald in the way it parses log messages that terminate with a colon ':'. A local attacker can use this flaw to disclose process memory data. Versions from v221 to v239 are vulnerable.

A buffer overflow vulnerability in the dhcp6 client of systemd allows a malicious dhcp6 server to overwrite heap memory in systemd-networkd. Affected releases are systemd: versions up to and including 239.

A race condition in chown_one() of systemd allows an attacker to cause systemd to set arbitrary permissions on arbitrary files. Affected releases are systemd versions up to and including 239.

A vulnerability in unit_deserialize of systemd allows an attacker to supply arbitrary state across systemd re-execution via NotifyAccess. This can be used to improperly influence systemd execution and possibly lead to root privilege escalation. Affected releases are systemd versions up to and including 239.

In systemd prior to 234 a race condition exists between .mount and .automount units such that automount requests from kernel may not be serviced by systemd resulting in kernel holding the mountpoint and any processes that try to use said mount will hang. A race condition like this may lead to denial of service, until mount points are unmounted.

systemd-tmpfiles in systemd through 237 mishandles symlinks present in non-terminal path components, which allows local users to obtain ownership of arbitrary files via vectors involving creation of a directory and a file under that directory, and later replacing that directory with a symlink. This occurs even if the fs.protected_symlinks sysctl is turned on.

systemd-tmpfiles in systemd before 237 attempts to support ownership/permission changes on hardlinked files even if the fs.protected_hardlinks sysctl is turned off, which allows local users to bypass intended access restrictions via vectors involving a hard link to a file for which the user lacks write access, as demonstrated by changing the ownership of the /etc/passwd file.

In systemd 223 through 235, a remote DNS server can respond with a custom crafted DNS NSEC resource record to trigger an infinite loop in the dns_packet_read_type_window() function of the 'systemd-resolved' service and cause a DoS of the affected service.

Stack-based buffer overflow in the getpwnam and getgrnam functions of the NSS module nss-mymachines in systemd.

systemd v233 and earlier fails to safely parse usernames starting with a numeric digit (e.g. "0day"), running the service in question with root privileges rather than the user intended.

In systemd through 233, certain sizes passed to dns_packet_new in systemd-resolved can cause it to allocate a buffer that's too small. A malicious DNS server can exploit this via a response with a specially crafted TCP payload to trick systemd-resolved into allocating a buffer that's too small, and subsequently write arbitrary data beyond the end of it.

systemd-resolved through 233 allows remote attackers to cause a denial of service (daemon crash) via a crafted DNS response with an empty question section.

A flaw in systemd v228 in /src/basic/fs-util.c caused world writable suid files to be created when using the systemd timers features, allowing local attackers to escalate their privileges to root. This is fixed in v229.

The manager_dispatch_notify_fd function in systemd allows local users to cause a denial of service (system hang) via a zero-length message received over a notify socket, which causes an error to be returned and the notification handler to be disabled.

The manager_invoke_notify_message function in systemd 231 and earlier allows local users to cause a denial of service (assertion failure and PID 1 hang) via a zero-length message received over a notify socket.

The session_link_x11_socket function in login/logind-session.c in systemd-logind in systemd, possibly 37 and earlier, allows local users to create or overwrite arbitrary files via a symlink attack on the X11 user directory in /run/user/.

The SetX11Keyboard function in systemd, when PolicyKit Local Authority (PKLA) is used to change the group permissions on the X Keyboard Extension (XKB) layouts description, allows local users in the group to modify the Xorg X11 Server configuration file and possibly gain privileges via vectors involving "special and control characters."

journald in systemd, when the origin of native messages is set to file, allows local users to cause a denial of service (logging service blocking) via a crafted file descriptor.

systemd, when updating file permissions, allows local users to change the permissions and SELinux security contexts for arbitrary files via a symlink attack on unspecified files.

Integer overflow in the valid_user_field function in journal/journald-native.c in systemd allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a large journal data field, which triggers a heap-based buffer overflow.

systemd does not properly use D-Bus for communication with a polkit authority, which allows local users to bypass intended access restrictions by leveraging a PolkitUnixProcess PolkitSubject race condition via a (1) setuid process or (2) pkexec process, a related issue to CVE-2013-4288.