CVE-2017-20002: The Debian shadow package before 1:4.5-1 for Shadow incorrectly lists pts/0 and pts/1 as physical terminals in

This month

HIGH 7.8WATCHLISTDOWNGRADEMITIGATE

CVE-2017-20002 is a high-severity flaw (CVSS 7.8) affecting shadow, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Debian shadow package before 1:4.5-1 for Shadow incorrectly lists pts/0 and pts/1 as physical terminals in /etc/securetty. This allows local users to login as password-less users even if they are connected by non-physical means such as SSH (hence bypassing PAM's nullok_secure configuration). This notably affects environments such as virtual machines automatically generated with a default blank root password, allowing all local users to escala

Why this priority

High severity
Public exploit reference
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

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 65%)
CISA exploited list	No
Weakness	CWE-269
Published	2021-03-17
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian

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

Am I affected?

Timeline

2021-03-17 06:15 UTCPublished CVE record published
2026-06-17 01:14 UTCUpdated Record last modified

debian shadow DOWNGRADE

Affected: 4.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.4 (Debian / Ubuntu)

apt-cache madison shadow sudo apt install shadow=<VERSION_BEFORE_4.4> sudo apt-mark hold shadow

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list shadow sudo dnf downgrade shadow-<VERSION_BEFORE_4.4> sudo dnf versionlock add shadow

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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.

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-2017-20002?

shadow: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-20002 being exploited?

CVE-2017-20002 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-2017-20002 affect?

CVE-2017-20002 affects shadow, debian linux. Severity is high (CVSS 7.8). The Debian shadow package before 1:4.5-1 for Shadow incorrectly lists pts/0 and pts/1 as physical terminals in /etc/securetty. This allows local users to login as password-less users even if they are connected by non-physical means such as

How urgent is CVE-2017-20002?

Priority 46/100. High severity; Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2023-29383 LOW 3.3 DOWNGRADE In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (cha
CVE-2013-4235 MEDIUM 4.7 MITIGATE MITIGATE shadow: TOCTOU (time-of-check time-of-use) race condition when copying and removing directory trees
CVE-2019-16110 HIGH 8.1 UPGRADE The network protocol of Blade Shadow though 2.13.3 allows remote attackers to take control of a Shadow instanc
CVE-2018-7169 MEDIUM 5.3 DOWNGRADE An issue was discovered in shadow 4.5
CVE-2018-16588 HIGH 7.8 UPGRADE Privilege escalation can occur in the SUSE useradd.c code in useradd, as distributed in the SUSE shadow packag

References

← Back to latest CVEs