Is CVE-2018-20839 in the CISA KEV catalog?

No. CVE-2018-20839 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2018-20839?

CVE-2018-20839 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2018-20839?

CVE-2018-20839 has an EPSS score of 2.48% (83th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2018-20839?

Upgrade plymouth on debian 11 to 0.9.4-1 or later.

CVE & CISA-KEV Catalog

CVE-2018-20839

MEDIUMEPSS 83th pctl

4.3

CVSS v3

NVD

Description

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 fix

Remediation Available

plymouthDebian

Fixed in:0.9.4-1CVE-2018-20839

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorPhysical

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Exploit Intelligence

2.48%probability of exploitation in 30 days

83rdpercentile

Elevated risk: more likely to be exploited than 83% of all known CVEs.

References

Patch2

Third-Party Advisory3

Mailing List1

lists.apache.org

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-05-05.