SB2020020548 - Ubuntu update for systemd
Published: February 5, 2020 Updated: October 30, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 5 vulnerabilities.
1) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2018-16888)
CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local attacker to escalate privileges on the system.
The vulnerability exists due to incorrect check the content of PIDFile files before using it to kill processes. A local attacker can who is able to write to the PIDFile of the mentioned service can trick systemd into killing other services and/or privileged processes.
2) Memory leak (CVE-ID: CVE-2019-20386)
CWE-ID: CWE-401 - Missing release of memory after effective lifetime
CVSSv4: 8.2 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H]
The vulnerability allows a local user to perform DoS attack on the target system.
The vulnerability exists due memory leak in button_open() function in login/logind-button.c in systemd. A remote attacker can execute the udevadm trigger command and perform denial of service attack.
3) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2019-3843)
CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to escalate privileges on the system.
The vulnerability exists due to an error in the process of binary creation, when the DynamicUser property is used to create a SUID or SGID binary for a systemd service. A local user can abuse the systemd functionality to execute arbitrary code on the target system with elevated privileges.
4) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2019-3844)
CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls
CVSSv4: 9.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H]
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to the 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 user 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.
5) Use-after-free (CVE-ID: CVE-2020-1712)
CWE-ID: CWE-416 - Use After Free
CVSSv4: 9.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H]
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use-after-free error when processing dbus messages during asynchronous Polkit queries in bus-polkit.c in systemd. A local unprivileged user can send a specially crafted dbus message, trigger a use-after-free error and crash services or execute arbitrary code on the system with elevated privileges.
Remediation
Install update from vendor's website.