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Ubuntu LinuxOperating system · Canonical

CVE-2019-9854

HIGH · 7.8 CVSS v3.1 Published 2019-09-06
Fix available
A fix is available. Upgrade to 6.2.7 / 6.3.1 or later.
See remediation →
81/100
Remediation priority · High
No privileges

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
LibreOffice has a feature where documents can specify that pre-installed macros can be executed on various script events such as mouse-over, document-open etc. Access is intended to be restricted to scripts under the share/Scripts/python, user/Scripts/python sub-directories of the LibreOffice install. Protection was added, to address CVE-2019-9852, to avoid a directory traversal attack where scripts in arbitrary locations on the file system could be executed by employing a URL encoding attack to defeat the path verification step. However this protection could be bypassed by taking advantage of a flaw in how LibreOffice assembled the final script URL location directly from components of the passed in path as opposed to solely from the sanitized output of the path verification step. This issue affects: Document Foundation LibreOffice 6.2 versions prior to 6.2.7; 6.3 versions prior to 6.3.1.

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

LibreOffice's macro execution feature (for events like document-open) was supposed to restrict scripts to share/Scripts/python or user/Scripts/python directories. A protection added for CVE-2019-9852 to prevent directory traversal could be bypassed because LibreOffice assembled the final script URL directly from components of the passed-in path rather than solely from the sanitized output of the path verification step, allowing arbitrary code execution via URL encoding tricks.

MitigationApply vendor patches (LibreOffice 6.2.7+ or 6.3.1+) or disable macro execution in LibreOffice settings to prevent untrusted documents from executing arbitrary code.

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
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 19.04
Debian LinuxOperating system
Affected:= 8.0= 9.0= 10.0
FedoraOperating system
Affected:= 29
Enterprise LinuxOperating system
Affected:= 7.0= 8.0
LibreofficeApplication
Affected:>= 6.2.0, < 6.2.7>= 6.3.0, < 6.3.1
LeapOperating system
Affected:= 15.0= 15.1

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
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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. Identify installed LibreOffice version
    Run 'libreoffice --version' or check the package manager (dpkg -l libreoffice* on Debian/Ubuntu, rpm -qi libreoffice on RHEL/Fedora, zypper se libreoffice on openSUSE)
    Affected if The installed version is >= 6.2.0 and < 6.2.7, OR >= 6.3.0 and < 6.3.1
  2. Verify macro execution is enabled
    In LibreOffice, go to Tools > Options > Security > Macro Security. Check the security level setting. Alternatively, inspect the configuration file ~/.config/libreoffice/4/user/registry/mainwindow.xcu or check for macro trusted paths.
    Affected if Macro security is set to Medium or Low (allowing macro execution), or untrusted document macros are permitted to run
  3. Confirm Python macro support is active
    Check if the Scripts/python directories exist in share/Scripts/python (system-wide) or user/Scripts/python (user home). On Linux these are typically under /usr/lib/libreoffice/share/Scripts/python and ~/.config/libreoffice/4/user/Scripts/python
    Affected if Python macro directories exist and are accessible, enabling the attack surface
  4. Check for untrusted document macro execution capability
    Attempt to create a test document with an embedded macro, or inspect the macro execution policy. On Linux, check the registry configuration at ~/.config/libreoffice/4/user/registry/data/org.openoffice.Office.Security.xcu for the MacroExecution policy
    Affected if Macros from untrusted locations (outside share/Scripts/python or user/Scripts/python) can be executed or the security policy permits this

A user is affected if they are running a vulnerable LibreOffice version (6.2.0-6.2.6 or 6.3.0-6.3.0) AND have macro execution enabled, allowing malicious documents to execute arbitrary code via URL-encoded path traversal.

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 6.2.7 / 6.3.1 or later
Fixed in 6.2.76.3.1
Interim mitigation

Apply vendor patches (LibreOffice 6.2.7+ or 6.3.1+) or disable macro execution in LibreOffice settings to prevent untrusted documents from executing arbitrary code.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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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-2019-9854 in production — separate from our analysis above.

No notes yet

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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