AIKIDO-2026-275945
fonttools is vulnerable to Path Traversal
55
Medium Risk
This Affects:
fonttoolsTL;DR
The fonttools varLib command line builds an output filename from the name attribute of a <variable-font> element in a designspace file. That value comes straight from the designspace and is joined into the output path without stripping directory components, so a name containing path traversal sequences writes the generated variable font outside the intended output directory and can overwrite files the process can access. The fix passes the name through os.path.basename before building the output path.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and you run the fonttools varLib command or call fontTools.varLib.main on an untrusted designspace file.
Background info
fonttools is vulnerable to Path Traversal in versions 4.40.0 - 4.64.0.
How to fix this
Upgrade the fonttools library to the patch version.
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SOC 2Compliant
ISO 27001CompliantISO 42001Compliant
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