CVE-2025-66034CWE-91

CVE-2025-66034

Medium · published November 29, 2025

CVSS v3.1
6.3
EPSS
1%
Percentile
45.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.3 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L
CVSS v4.0
Not supplied
EPSS
0.00547 · 45.1th percentile
Weakness
CWE-91 · XML Injection (aka Blind XPath Injection)
Published
2025-11-29T06:16Z
Affected products (1)
ProductVersionsFixed in
fonttools/fonttools≥ 4.33.0, < 4.60.24.60.2
References (3)
https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fv · [email protected]https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fv · 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32 · [email protected]
EPSS history
Timeline
  • 29 NOV 01:07Z
    fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib
    cvelistv5