Path traversal in fontTools - CVE-2025-66034
Published: November 28, 2025 / Updated: April 1, 2026
Vulnerability identifier: #VU118845
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/U:Amber
CVE-ID: CVE-2025-66034
CWE-ID: CWE-22
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vendor: FontTools
Affected software:
fontTools
fontTools
Detailed vulnerability description
The vulnerability allows a remote attacker to compromise the affected system.
The vulnerability exists due to input validation error when processing .designspace files in fontTools.varLib. A remote attacker can trick the victim into passing a specially crafted file and overwrite arbitrary files on the system.
How to mitigate CVE-2025-66034
Install updates from vendor's website.