OrcaSlicer Patches a Flaw That Let Malicious 3MF Files Overwrite Your Data

We covered the previous stable release in October 2025 and, like its predecessor, this update also fixes a few bugs and adds new features. The most headline-grabbing aspect is the addressing of a security vulnerability with 3MF file imports, which hadn’t been disclosed before.

The information provided in the GitHub release notes refers to a fix that prevents the opening of .3mf files – increasingly the go-to for complex multi-plate or multicolor projects – from writing files to arbitrary locations on your system, which could then, potentially, execute malicious code.

3MF files are, essentially, a kind of ZIP folder. You don’t ever interact with them as you would a regular ZIP, because your slicer handles the unpacking tidily in the background. This type of vulnerability, colloquially known as a “zip-slip“, benefits from that. SoftFever, lead maintainer of OrcaSlicer, told us: “In plain terms: a malicious actor could craft a specially made .3mf file that, when opened in Orca Slicer, would silently write attacker-controlled files to arbitrary locations on the user’s disk – outside of where OrcaSlicer is supposed to touch…” They continue, “just opening a “project file” from an untrusted source could compromise your machine.”

Such files could, theoretically, be uploaded to model repositories, appear and function as regular printable files, and exploit your system when you download and use them. We’re not aware of any reported uses of this exploit happening in the wild.

“The issue was responsibly reported to us by user ‘Zekun Shen’, who deserves a lot of credit – he provided a thorough analysis, a working proof-of-concept, and even detailed steps on how such a malicious .3mf could be crafted.” SoftFever continues. “That made it much easier for us to understand the full scope and patch it quickly.”

Orca Slicer being a fork of Bambu Studio, itself derived from PrusaSlicer, begs the obvious question of whether this vulnerability exists upstream in those slicers, too. SoftFever tells us the issue was inherited from the initial forking of Bambu Studio.

A Bambu Lab representative told us that “Bambu Studio does not contain this vulnerability”. We’ve yet to hear from Prusa whether the any such issue exists in their slicer, too. It logically follows that downstream slicers forked from versions of Orca before V2.3.2 will need to fold this fix into their codebases too, if they haven’t already.