# CVE-2025-66034: fonttools: fontTools is a library for manipulating fonts, written in Python

CVE-2025-66034 is fixed in 3 products on 1 platform, first by fonttools 4.46.0-1ubuntu0.1~esm1, released November 28, 2025. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2025-66034
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0059
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 28, 2025

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | fonttools Debian 12.15 (bookworm) | 4.38.0-1+deb12u1 | [DEBIAN-CVE-2025-66034](https://patchblox.com/security/data/fix/linux/debian-cve-2025-66034.md) | Nov 29, 2025 |
| Linux | fonttools Debian 13.5 (trixie) | 4.57.0-1+deb13u1 | [DEBIAN-CVE-2025-66034](https://patchblox.com/security/data/fix/linux/debian-cve-2025-66034.md) | Nov 29, 2025 |
| Linux | fonttools Debian 14 | 4.61.1-1 | [DEBIAN-CVE-2025-66034](https://patchblox.com/security/data/fix/linux/debian-cve-2025-66034.md) | Nov 29, 2025 |
| Linux | fonttools Ubuntu 24.04.5 LTS (noble) | 4.46.0-1ubuntu0.1~esm1 | [fonttools 4.46.0-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-fonttools-4.46.0-1ubuntu0.1-esm1.md) | Nov 28, 2025 |
| Linux | fonttools Ubuntu 25.10 (questing) | 4.55.3-2ubuntu0.25.10.1 | [fonttools 4.55.3-2ubuntu0.25.10.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-fonttools-4.55.3-2ubuntu0.25.10.1.md) | Nov 28, 2025 |
| Linux | fonttools Ubuntu 26.04.1 LTS (resolute) | 4.57.0-3ubuntu1 | [fonttools 4.57.0-3ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-fonttools-4.57.0-3ubuntu1.md) | Nov 28, 2025 |
| Linux | python-FontTools opensuse-leap 15.6 | 4.47.2-150600.3.3.1 | [SUSE-SU-2026:0199-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0199-1.md) | Jan 21, 2026 |
| Linux | python-FontTools opensuse-leap 16.0 | 4.53.1-160000.3.1 | [OPENSUSE-SU-2026:20119-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20119-1.md) | Jan 28, 2026 |
| Linux | python-FontTools sles 15.7 | 4.47.2-150600.3.3.1 | [SUSE-SU-2026:0199-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0199-1.md) | Jan 21, 2026 |
| Linux | python-FontTools sles 16.0 | 4.53.1-160000.3.1 | [SUSE-SU-2026:20184-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-20184-1.md) | Jan 28, 2026 |
| Linux | python3-fonttools Ubuntu 24.04.5 LTS (noble) | 4.46.0-1ubuntu0.1~esm1 | [python3-fonttools 4.46.0-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-python3-fonttools-4.46.0-1ubuntu0.1-esm1.md) | Nov 28, 2025 |
| Linux | python3-fonttools Ubuntu 25.10 (questing) | 4.55.3-2ubuntu0.25.10.1 | [python3-fonttools 4.55.3-2ubuntu0.25.10.1](https://patchblox.com/security/data/fix/linux/ubuntu-questing-python3-fonttools-4.55.3-2ubuntu0.25.10.1.md) | Nov 28, 2025 |
| Linux | python3-fonttools Ubuntu 26.04.1 LTS (resolute) | 4.57.0-3ubuntu1 | [python3-fonttools 4.57.0-3ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-fonttools-4.57.0-3ubuntu1.md) | Nov 28, 2025 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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