XML Injection Affecting fonttools package, versions <4.55.3-2ubuntu0.25.10.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.55% (44th percentile)

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  • Snyk IDSNYK-UBUNTU2510-FONTTOOLS-14155403
  • published9 Dec 2025
  • disclosed29 Nov 2025

Introduced: 29 Nov 2025

CVE-2025-66034  (opens in a new tab)
CWE-91  (opens in a new tab)

How to fix?

Upgrade Ubuntu:25.10 fonttools to version 4.55.3-2ubuntu0.25.10.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream fonttools package and not the fonttools package as distributed by Ubuntu. See How to fix? for Ubuntu:25.10 relevant fixed versions and status.

fontTools is a library for manipulating fonts, written in Python. In versions from 4.33.0 to before 4.60.2, the fonttools varLib (or python3 -m fontTools.varLib) script has an arbitrary file write vulnerability that leads to remote code execution when a malicious .designspace file is processed. The vulnerability affects the main() code path of fontTools.varLib, used by the fonttools varLib CLI and any code that invokes fontTools.varLib.main(). This issue has been patched in version 4.60.2.

CVSS Base Scores

version 3.1