CVE-2019-20373: LTSP LDM through 2.18.06 allows fat-client root access because the LDM_USERNAME variable may have an empty val

Q: How do I fix CVE-2019-20373?

debian linux: mitigate or apply the listed mitigation; ldm: upgrade to newer than 2.18.06. Exact commands for each OS are on this page.

Q: Is CVE-2019-20373 being exploited?

CVE-2019-20373 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-20373 affect?

CVE-2019-20373 affects debian linux, ldm. Severity is high (CVSS 7.8). LTSP LDM through 2.18.06 allows fat-client root access because the LDM_USERNAME variable may have an empty value if the user's shell lacks support for Bourne shell syntax. This is related to a run-x-session script.

Q: How urgent is CVE-2019-20373?

Priority 42/100. High severity; On your watchlist

This month

HIGH 7.8WATCHLISTMITIGATEUPGRADE

CVE-2019-20373 is a high-severity flaw (CVSS 7.8) affecting debian linux, ldm. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LTSP LDM through 2.18.06 allows fat-client root access because the LDM_USERNAME variable may have an empty value if the user's shell lacks support for Bourne shell syntax. This is related to a run-x-session script.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 61%)
CISA exploited list	No
Published	2020-01-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · ltsp

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-01-09 23:15 UTCPublished CVE record published
2026-06-17 02:30 UTCUpdated Record last modified

debian debian linux MITIGATE

Affected: 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ltsp ldm UPGRADE

Affected: <= 2.18.06

Fixed in: newer than 2.18.06

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy ldm || rpm -q ldm || ldm --version

2. UPGRADE to newer than 2.18.06 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ldm

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ldm

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-20373?

debian linux: mitigate or apply the listed mitigation; ldm: upgrade to newer than 2.18.06. Exact commands for each OS are on this page.

Is CVE-2019-20373 being exploited?

CVE-2019-20373 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2019-20373 affect?

CVE-2019-20373 affects debian linux, ldm. Severity is high (CVSS 7.8). LTSP LDM through 2.18.06 allows fat-client root access because the LDM_USERNAME variable may have an empty value if the user's shell lacks support for Bourne shell syntax. This is related to a run-x-session script.

How urgent is CVE-2019-20373?

Priority 42/100. High severity; On your watchlist

Software pages

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References

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