Unity DirectTMP is an editor tool and a small runtime component. It is worth being precise about what it does, because two of its features sound alarming until they are described exactly.

It reads font files. DirectFontFile parses the name, maxp, head and cmap tables of .ttf / .otf / .ttc files — the ones in your project, and the ones installed on your machine when you switch the Font Catalog's "Installed fonts" toggle on. It is a read-only parse into a bounds-checked buffer. Nothing is executed, nothing is written back, and no font file is copied anywhere.

It changes the Unity Editor's UI font. Only in memory, only for the current session, and only across GUIStyle and GUISkin objects that Unity has already loaded. It writes nothing into your Unity installation, edits no built-in asset on disk, and installs no startup hook outside the package. Quitting Unity restores everything.

It writes exactly two kinds of thing to disk. Preferences, via EditorPrefs, keyed per project; and spooled copies of fonts you hand it as a raw byte[], under Application.persistentDataPath/UnityDirectTMP/FontCache, which the Clear Cache menu item deletes.

It makes no network requests. There is no telemetry, no analytics, no update check and no licence server. The only URLs in the package are the ones behind buttons a person clicks, which open in the system browser.

Please do not open a public issue for a security problem.

Email amircollider@yahoo.com with:

• what you found, and where in the package
• how to reproduce it — a crafted font file is the most useful attachment here
• what an attacker could do with it

You will get an acknowledgement within a few days. A confirmed issue is fixed in a patch release, credited to you unless you would rather not be.

The font parser is the part of this package most worth attacking, because it is the only place that reads bytes it did not write. A malformed or hostile font file that makes DirectFontFile.Parse throw an unhandled exception, read out of bounds, allocate unboundedly, or hang the Editor is a genuine bug and is in scope — even though the parse is managed C# and cannot corrupt memory. It is supposed to return an invalid result with a reason, every time, for every input.

Also in scope: anything that makes the Editor-font override persist past a Unity restart, or that gets past the guard that refuses a font which cannot draw the Editor's own interface. Both would leave somebody with an Editor they cannot undo the change from.

Out of scope: the fact that a font file you choose to load is executed by FreeType inside Unity's own FontEngine (that is Unity's surface, not this package's), and anything requiring the attacker to already be able to write arbitrary files into your project.

The latest release. This is a small, free package; fixes go forward rather than into old versions.