CVE-2019-9854 Unsafe URL assembly flaw in allowed script location check

What is CVE-2019-9854?

CVE-2019-9854 is a high-severity path traversal vulnerability in Canonical Ubuntu Linux, published on 6 Sep 2019. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-22

Which versions are affected by CVE-2019-9854?

It affects 6 products.

Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Libreoffice Libreoffice, Opensuse Leap, Redhat Enterprise Linux.

How do I fix CVE-2019-9854?

Upgrade to a fixed version.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2019-9854 being exploited?

There is no known exploitation of CVE-2019-9854 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2019-9854, DSA-4519-1, GHSA-54x7-phmv-8vq8, UBUNTU-CVE-2019-9854, USN-4138-1.