Credentials management in systemd - CVE-2018-20839
Published: May 17, 2019 / Updated: August 8, 2020
Vulnerability identifier: #VU35894
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2018-20839
CWE-ID: CWE-255
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Freedesktop.org
Affected software:
systemd
systemd
Detailed vulnerability description
The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.
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.
How to mitigate CVE-2018-20839
Install update from vendor's website.