XPath Injection in Fonttools
CVE-2025-66034
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.
EPSS: 0.006 (43.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L.
Affected products
- Fonttools — versions >= 4.33.0, < 4.60.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2025-66034?
- CVE-2025-66034 is a medium-severity vulnerability in Fonttools, classified under XML Injection (Blind XPath Injection). CVSS score: 6.3/10. Published 2025-11-29.
- How severe is CVE-2025-66034?
- Medium severity. CVSS v3 base score is 6.3 out of 10.
- Is CVE-2025-66034 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.