dbcve.org
FedoraOperating system · Fedoraproject

CVE-2019-20044

HIGH · 7.8 CVSS v3.1 Published 2020-02-24
Fix available
A fix is available. Upgrade to 5.8 / 6.2.5 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In Zsh before 5.8, attackers able to execute commands can regain privileges dropped by the --no-PRIVILEGED option. Zsh fails to overwrite the saved uid, so the original privileges can be restored by executing MODULE_PATH=/dir/with/module zmodload with a module that calls setuid().

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Zsh before 5.8, the shell's --no-PRIVILEGED option fails to properly overwrite the saved UID when dropping privileges. This allows an attacker with command execution to restore their original elevated privileges by loading a malicious module via zmodload that calls setuid(), bypassing the intended privilege dropping mechanism.

MitigationUpgrade to Zsh 5.8 or later. Avoid setting MODULE_PATH to untrusted directories when using --no-PRIVILEGED mode, and audit any custom modules for setuid() calls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 30= 31
Debian LinuxOperating system
Affected:= 8.0= 9.0
ZshApplication
Affected:< 5.8
IpadosOperating system
Affected:< 13.5
Iphone OsOperating system
Affected:< 13.5
Mac Os XOperating system
Affected:< 10.15.5>= 10.13.0, < 10.13.6>= 10.14.0, < 10.14.6>= 10.15, < 10.15.5= 10.13.6= 10.14.6
TvosOperating system
Affected:< 13.4.5
WatchosOperating system
Affected:< 6.2.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Zsh version
    Run 'zsh --version' or 'zmodload' then 'echo $ZSH_VERSION' to determine the version
    Affected if Version is before 5.8 (e.g., 5.7.1, 5.7, etc.)
  2. Verify --no-PRIVILEGED mode is in use
    Inspect how Zsh is invoked: check shell scripts, cron jobs, systemd units, or command lines for the '--no-PRIVILEGED' or '-u' flag
    Affected if Zsh is invoked with --no-PRIVILEGED or -u flag to drop privileges
  3. Inspect MODULE_PATH for untrusted directories
    Run 'echo $MODULE_PATH' in the affected Zsh environment to list module search paths
    Affected if MODULE_PATH includes world-writable or untrusted directories (e.g., /tmp, shared network paths)
  4. Audit loaded modules for setuid capability
    Run 'zmodload' to list loaded modules, then inspect any custom/third-party modules in MODULE_PATH for calls to the setuid() C function
    Affected if A custom module containing setuid() calls is loadable from the configured MODULE_PATH

You are affected if running Zsh version below 5.8 with the --no-PRIVILEGED option enabled and a malicious or compromised module with setuid() capability is loadable from the configured MODULE_PATH.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 5.8 / 6.2.5 / 10.13.6 or later
Fixed in 5.86.2.510.13.6
Interim mitigation

Upgrade to Zsh 5.8 or later. Avoid setting MODULE_PATH to untrusted directories when using --no-PRIVILEGED mode, and audit any custom modules for setuid() calls.

Fix this in Fedora Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2019-20044 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-20044 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data