USN-7917-1: fontTools vulnerabilities

Publication date

9 December 2025

Overview

Several security issues were fixed in fontTools.


Packages

  • fonttools - a library for manipulating fonts, written in Python

Details

It was discovered that the subsetting module of fontTools was vulnerable to
an XML External Entity (XEE) attack. An unauthenticated remote attacker
could possibly use this issue to include arbitrary files from the file
system or make web requests from the host system. This issue only affected
Ubuntu 22.04 LTS. (CVE-2023-45139)

It was discovered that fontTools was vulnerable to path traversal attacks.
If a user or automated system were tricked into extracting a specially
crafted .designspace file, an attacker could possibly use this issue to
write arbitrary files outside the target directory, resulting in remote
code execution. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04
and Ubuntu 25.10. (CVE-2025-66034)

It was discovered that the subsetting module of fontTools was vulnerable to
an XML External Entity (XEE) attack. An unauthenticated remote attacker
could possibly use this issue to include arbitrary files from the file
system or make web requests from the host system. This issue only affected
Ubuntu 22.04 LTS. (CVE-2023-45139)

It was discovered that fontTools was vulnerable to path traversal attacks.
If a user or automated system were tricked into extracting a specially
crafted .designspace file, an attacker could possibly use this issue to
write arbitrary files outside the target directory, resulting in remote
code execution. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04
and Ubuntu 25.10. (CVE-2025-66034)

Update instructions

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
25.10 questing fonttools –  4.55.3-2ubuntu0.25.10.1
python3-fonttools –  4.55.3-2ubuntu0.25.10.1
25.04 plucky fonttools –  4.55.3-2ubuntu0.25.04.1
python3-fonttools –  4.55.3-2ubuntu0.25.04.1
24.04 LTS noble fonttools –  4.46.0-1ubuntu0.1~esm1  
python3-fonttools –  4.46.0-1ubuntu0.1~esm1  
22.04 LTS jammy fonttools –  4.29.1-2ubuntu0.1~esm1  
python3-fonttools –  4.29.1-2ubuntu0.1~esm1  

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