CVE-2018-20839

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.

Published: 2019-05-17 Last update: 2025-05-05 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-20839 is rated Moderate Risk (41.8/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.63%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-20839

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-17 0.67% 0.63% -0.04%
2 2025-11-21 0.78% 0.67% -0.11%
3 2025-11-18 — 0.78% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-20839

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.7 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2018-20839

OS Trackers for CVE-2018-20839

vendor priority summary link
debian low CVE-2018-20839 low priority: Debian including 1 source packages (plymouth), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-20839
redhat medium — https://access.redhat.com/security/cve/CVE-2018-20839
ubuntu medium CVE-2018-20839 medium priority: Ubuntu including 1 source packages (systemd), 12 status rows across 12 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 8, ignored 3, needed 1. https://ubuntu.com/security/CVE-2018-20839

Affected software / configurations for CVE-2018-20839

Vendor Product Version Raw CPE
systemd_project systemd 242 cpe:2.3:a:systemd_project:systemd:242:-:*:*:*:*:*:*
netapp cn1610_firmware — cpe:2.3:o:netapp:cn1610_firmware:-:*:*:*:*:*:*:*
netapp snapprotect — cpe:2.3:a:netapp:snapprotect:-:*:*:*:*:*:*:*
netapp solidfire_\&_hci_management_node — cpe:2.3:a:netapp:solidfire_\&_hci_management_node:-:*:*:*:*:*:*:*

References for CVE-2018-20839

cvelogic Threat Intelligence