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[USN-7917-1] fontTools vulnerabilities

Posted on 09 December 2025
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-7917-1
December 09, 2025

fonttools vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 25.10
- Ubuntu 25.04
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Several security issues were fixed in fontTools.

Software Description:
- 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)

Update instructions:

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

Ubuntu 25.10
fonttools 4.55.3-2ubuntu0.25.10.1
python3-fonttools 4.55.3-2ubuntu0.25.10.1

Ubuntu 25.04
fonttools 4.55.3-2ubuntu0.25.04.1
python3-fonttools 4.55.3-2ubuntu0.25.04.1

Ubuntu 24.04 LTS
fonttools 4.46.0-1ubuntu0.1~esm1
Available with Ubuntu Pro
python3-fonttools 4.46.0-1ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 22.04 LTS
fonttools 4.29.1-2ubuntu0.1~esm1
Available with Ubuntu Pro
python3-fonttools 4.29.1-2ubuntu0.1~esm1
Available with Ubuntu Pro

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

References:
https://ubuntu.com/security/notices/USN-7917-1
CVE-2023-45139, CVE-2025-66034

Package Information:
https://launchpad.net/ubuntu/+source/fonttools/4.55.3-2ubuntu0.25.10.1
https://launchpad.net/ubuntu/+source/fonttools/4.55.3-2ubuntu0.25.04.1

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