CVE-2025-66034 MEDIUM

CVE-2025-66034: fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib

Vendor Fonttools
Product fonttools
Weakness CWE-91 · XML injection
Published November 29, 2025
Last update December 1, 2025
View on NVD All CVEs

CVSS base score

6.3/10
Attack vector Local
Attack complexity High
Privileges required None
User interaction Required
Confidentiality None
Integrity High

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

November 29, 2025 CVE published
December 1, 2025 Record updated