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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| fonttools | fonttools | >= 4.33.0, < 4.60.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | fonttools | 4.61.1-1 | — |
| Debian 13 | fonttools | 4.57.0-1+deb13u1 | — |
| Debian 12 | fonttools | 4.38.0-1+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | fonttools | 4.57.0-3ubuntu1 | — |
| Ubuntu 25.10 | fonttools | 4.55.3-2ubuntu0.25.10.1 | USN-7917-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | fonttools | 4.46.0-1ubuntu0.1~esm1 | USN-7917-1 |
| Ubuntu Pro 22.04 LTS | fonttools | 4.29.1-2ubuntu0.1~esm1 | USN-7917-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | python-FontTools | 4.47.2-150600.3.3.1 | SUSE-SU-2026:0199-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | python-FontTools | 4.53.1-160000.3.1 | SUSE-SU-2026:20184-1 |
| SLES 16.0 | python-FontTools | 4.53.1-160000.3.1 | SUSE-SU-2026:20184-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-FontTools | 4.61.1-1.1 | openSUSE-SU-2026:10076-1 |
| openSUSE Leap 16.0 | python-FontTools | 4.53.1-160000.3.1 | openSUSE-SU-2026:20119-1 |
| openSUSE Leap 15.6 | python-FontTools | 4.47.2-150600.3.3.1 | SUSE-SU-2026:0199-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | open-webui | 0.8.12-r4 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 6 repositories
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v3cn4x00/POC-CVE-2025-66034 ★ 4 · Mar 21, 2026
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Liquid-Sec/Variatype.htb-CVE-2025-66034 ★ 2 · Mar 16, 2026
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symphony2colour/varlib-cve-2025-66034 ★ 2 · Mar 15, 2026
Proof-of-concept exploit for CVE-2025-66034 in the fontTools variable font generation pipeline. A crafted .designspace file allows control of the output path, enabling arbitrary file writes. The scri…
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jwsly12/CVE-2025-66034-htb-ctf ★ 1 · Apr 7, 2026
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tristanqtn/CVE-2025-66034 ★ 1 · Mar 20, 2026
CVE-2025-66034 exploit and documentation
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4nuxd/CVE-2025-66034 ★ 0 · Mar 28, 2026
CVE-2025-66034 - fontTools varLib Arbitrary File Write → RCE PoC exploit for an Arbitrary File Write + XML Injection vulnerability in fontTools.varLib.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | fonttools | >= 4.33.0, < 4.60.2 | 4.60.2 | GHSA-768j-98cg-p3fv |
Advisories 6
- WID-SEC-2026-2189 Dell PowerProtect Data Domain: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 2, 2026
- USN-7917-1 fonttools vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- openSUSE-SU-2026:20119-1 Security update for python-FontTools SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10076-1 python311-FontTools-4.61.1-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20184-1 Security update for python-FontTools SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:0199-1 Security update for python-FontTools SUSE / openSUSE Security Updates · Mar 23, 2026