Please report suspected vulnerabilities privately through GitHub Security Advisories at https://github.com/excelano/slipcase-desktop/security/advisories/new. If you would rather not use GitHub, email david.anderson@excelano.com instead. I aim to respond within seven days.

Please do not open public issues for security problems.

The latest 0.x release receives security fixes. Older versions are not supported.

Slipcase opens a container someone may have sent you, shows its metadata, and hands the payload to whatever your operating system has registered for it. It runs locally, makes no network call of any kind, has no account and no telemetry, and can read and write only what your operating-system user already can.

Containers are read and written entirely through slpc, the library in excelano/slpc-rust, which has a security policy of its own covering the format and the command-line tool. This document covers the window.

One line. The directory of the last container you opened is written to $XDG_STATE_HOME/slipcase-desktop/last-folder — %APPDATA% or ~/Library/Application Support on the other two platforms — so the file dialog opens somewhere useful. Nothing else is kept, nothing is sent anywhere, and deleting that file removes it.

Payloads you press Open on are extracted to a private temporary directory, mode 0700, which is removed when the application exits.

It does not decide whether a payload is safe to open. The card says what the platform said would open the payload, and the Open button hands the file to the platform. This application ships no table mapping filenames to types, does not inspect a payload's contents to guess at one, and does not substitute its own judgement for the operating system's about what is dangerous. What it adds is information: where the container came from, and whether the payload was stored as an executable file.

It carries provenance rather than stripping it. A container marked by the platform as having arrived from elsewhere — com.apple.quarantine, a Zone.Identifier stream, user.xdg.origin.url — passes that mark to the payload extracted from it and keeps it on the container when you edit and save. Without that, an application like this one is a tool for laundering the mark, which is the property that made container attachments a favoured delivery mechanism. Both halves were defects here once and both are recorded in CHECKLIST.md and in the git log.

Slipcase reports whether a container conforms to the format specification. That is a statement about the file's structure and says nothing about whether its payload is safe, whether the container is what it claims to be, or who produced it. The format defines no signature, no checksum, and no encryption of its own.

Every release lists a SHA-256 for each artefact. Verify a download before running it.