CVE-2025-66034
fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib
CRITICAL 9.8EPSS 0.5%
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
- fonttools
- CVSS v3.1 NVD
- 9.8 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS v3.1 GITHUB
- 6.3 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L - EPSS
- 0.55% chance of exploitation in the next 30 days, 45th percentile
- Published
- 2025-11-29
- Updated
- 2025-12-01
Proof-of-concept exploits (8)
- advisories/GHSA-768j-98cg-p3fv
- symphony2colour/varlib-cve-2025-660342★ · 2026-08-31
- 4nuxd/CVE-2025-660340★ · 2026-03-28
- Liquid1998/Variatype.htb-CVE-2025-660342★ · 2026-03-16
- tristanqtn/CVE-2025-660341★ · 2026-03-29
- v3cn4x00/POC-CVE-2025-660344★ · 2026-03-21
- ConradKash/exploit0★ · 2026-03-17
- Liquid-Sec/Variatype.htb-CVE-2025-660342★ · 2026-03-16
Security advisories
- fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fv
- fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32