CVE-2025-66034

Name: CVE-2025-66034
Creator: NVD / NIST
Published: 2025-11-29T01:16:02.967+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.49%

Last modified Jun 17, 2026

CVE-2025-66034 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 0.49% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.49%

38.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-91

Affected Software

Vendor	Product	Versions
Fonttools	Fonttools	>= 4.33.0, < 4.60.2

References

https://github.com/fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32Patch
https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fvExploit, Vendor Advisory
https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fvExploit, Vendor Advisory

Timeline

Published: Nov 29, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-66034?

How severe is CVE-2025-66034?

CVE-2025-66034 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2025-66034?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2025-66034?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST