Is CVE-2025-66034 actively exploited?

No active exploitation of CVE-2025-66034 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2025-66034 be exploited remotely?

Yes. CVE-2025-66034 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2025-66034?

CVE-2025-66034 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2025-66034

CWE-91Published: November 29, 2025· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2025-66034 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.