CVE-2019-5021: Versions of the Official Alpine Linux Docker images (since v3.3) contain a NULL password for the `root` user

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CRITICAL 9.8REMOTEWATCHLISTDOWNGRADEMITIGATEDOWNGRADE

CVE-2019-5021 is a critical-severity flaw (CVSS 9.8) affecting docker-alpine, leap, big-ip controller. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Versions of the Official Alpine Linux Docker images (since v3.3) contain a NULL password for the `root` user. This vulnerability appears to be the result of a regression introduced in December of 2015. Due to the nature of this issue, systems deployed using affected versions of the Alpine Linux container which utilize Linux PAM, or some other mechanism which uses the system shadow file as an authentication database, may accept a NULL password for

Why this priority

Critical severity
EPSS top 6%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	6.3% (top 6%)
CISA exploited list	No
Weakness	CWE-258
Published	2019-05-08
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: f5 · gliderlabs · opensuse

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

Am I affected?

Timeline

2019-05-08 17:29 UTCPublished CVE record published
2026-06-17 02:37 UTCUpdated Record last modified

gliderlabs docker-alpine DOWNGRADE

Affected: >= 3.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.3

1. Check installed version

apt-cache policy docker-alpine || rpm -q docker-alpine || docker-alpine --version

2. No fixed release: DOWNGRADE to a release before 3.3 (Debian / Ubuntu)

apt-cache madison docker-alpine sudo apt install docker-alpine=<VERSION_BEFORE_3.3> sudo apt-mark hold docker-alpine

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

dnf --showduplicates list docker-alpine sudo dnf downgrade docker-alpine-<VERSION_BEFORE_3.3> sudo dnf versionlock add docker-alpine

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.

opensuse leap MITIGATE

Affected: 15.0 · 15.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

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.

f5 big-ip controller DOWNGRADE

Affected: 1.2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.2.1

1. Check installed version

apt-cache policy big-ip-controller || rpm -q big-ip-controller || big-ip-controller --version

2. No fixed release: DOWNGRADE to a release before 1.2.1 (Debian / Ubuntu)

apt-cache madison big-ip-controller sudo apt install big-ip-controller=<VERSION_BEFORE_1.2.1> sudo apt-mark hold big-ip-controller

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

dnf --showduplicates list big-ip-controller sudo dnf downgrade big-ip-controller-<VERSION_BEFORE_1.2.1> sudo dnf versionlock add big-ip-controller

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · python-discovery · FIXED · 1.9.0-1.eln159 · FEDORA-2026-7a881c0c99 · source

sudo dnf upgrade --advisory=FEDORA-2026-7a881c0c99

Fedora 46 · pipx · FIXED · 1.18.11-1.fc46 · FEDORA-2026-443a765287 · source

sudo dnf upgrade --advisory=FEDORA-2026-443a765287

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: talosintelligence.com/vulnerability_reports/TALOS-2019-0782
GitHub PoC: mawinkler/c1-cs-smartcheck-cve-2019-5021

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-2019-5021?

docker-alpine: downgrade or apply the listed mitigation; leap: mitigate or apply the listed mitigation; big-ip controller: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-5021 being exploited?

CVE-2019-5021 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-2019-5021 affect?

CVE-2019-5021 affects docker-alpine, leap, big-ip controller. Severity is critical (CVSS 9.8). Versions of the Official Alpine Linux Docker images (since v3.3) contain a NULL password for the `root` user. This vulnerability appears to be the result of a regression introduced in December of 2015. Due to the nature of this issue, syste

How urgent is CVE-2019-5021?

Priority 73/100. Critical severity; EPSS top 6%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Docker vulnerabilities · F5 BIG-IP vulnerabilities

References

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