CVE-2025-66034
Medium
Description
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.
SeverityMedium
CVSS6.3
Exploit probability—
ProductFonttools
PublishedNov 29, 2025
First seenNov 29, 2025
Weakness typeCWE-91CWE-91
How to fix
Update
- fonttools fonttools4.60.2 or later
- fonttools4.60.2 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| fonttools fonttools | 4.33.0 ≤ v < 4.60.2 | 4.60.2 |
| fonttoolsPyPI | 4.33.0 ≤ v < 4.60.2 | 4.60.2 |
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