CVE-2025-66034fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 6.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L
- Weakness (CWE)
- CWE-91
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Dec 1, 2025
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
fonttools fonttools fonttools:fonttools (from the name) | from 4.33.0, < 4.60.2 | CNA record |
fonttools fonttools fonttools:fonttools | from 4.33.0 before 4.60.2 | NVD |
References
- https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fvx-refsource-confirm, exploit, vendor-advisory
- https://github.com/fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32x-refsource-misc, patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.