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Debian LinuxOperating system · Debian

CVE-2020-17368

CRITICAL · 9.8 CVSS v3.1 Published 2020-08-11
Fix available
A fix is available. Upgrade to after 0.9.62 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Firejail through 0.9.62 mishandles shell metacharacters during use of the --output or --output-stderr option, which may lead to command injection.

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 · moderate confidence

Firejail through version 0.9.62 contains a command injection vulnerability in the --output and --output-stderr options. These options fail to properly sanitize shell metacharacters, allowing an attacker to inject arbitrary commands through crafted arguments.

MitigationAvoid using the --output and --output-stderr options in vulnerable versions, or upgrade to a patched version of Firejail that properly escapes shell metacharacters in output filename parameters.

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
Debian LinuxOperating system
Affected:= 9.0= 10.0
FedoraOperating system
Affected:= 31= 32
FirejailApplication
Affected:<= 0.9.62
LeapOperating system
Affected:= 15.2

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Determine installed Firejail version
    Run 'firejail --version' or check your package manager (dpkg -l firejail, rpm -q firejail, etc.)
    Affected if Version is 0.9.62 or lower
  2. Identify use of --output option
    Search configuration files, scripts, and command history for 'firejail --output' patterns using grep -r 'firejail.*--output' /etc /home or similar paths
    Affected if The --output option is used with user-controlled filename parameters
  3. Identify use of --output-stderr option
    Search configuration files, scripts, and command history for 'firejail --output-stderr' patterns
    Affected if The --output-stderr option is used with user-controlled filename parameters
  4. Review argument sources for shell metacharacters
    Inspect any scripts or automation that invoke Firejail with --output or --output-stderr, checking if filename arguments could contain characters like $(); |; &; &&; ||; >; <; `
    Affected if Filename arguments passed to --output or --output-stderr accept unsanitized input containing shell metacharacters

You are affected if Firejail version is 0.9.62 or lower AND the --output or --output-stderr options are used with arguments that could contain unsanitized shell metacharacters.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 0.9.62
Interim mitigation

Avoid using the --output and --output-stderr options in vulnerable versions, or upgrade to a patched version of Firejail that properly escapes shell metacharacters in output filename parameters.

Recommended fix High confidence

Firejail 0.9.63 or later (fixed release)

  1. 1. Identify the installed Firejail version using: firejail --version
  2. 2. If version is 0.9.62 or lower, update the Firejail package through your distribution's package manager
  3. 3. For Debian/Ubuntu: run 'apt update && apt install firejail'
  4. 4. For Fedora: run 'dnf update firejail'
  5. 5. For openSUSE Leap: run 'zypper update firejail'
  6. 6. Verify the upgrade was successful by checking: firejail --version
  7. 7. Ensure the new version is 0.9.63 or later which contains the fix for shell metacharacter handling in --output and --output-stderr options

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2020-17368 in production — separate from our analysis above.

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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