CVE-2025-66034

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.

Affected products

Debian, Linuxmint, Ubuntu, Fonttools

Fonttools

< 4.60.2

Fix

Available

CVSS 3.1

9.8 CRITICAL

EPSS

0.5% (44th percentile)

Weakness

CWE-91

NVD status

Analyzed

Published

2025-11-29