LocalSend is a free, open-source app that allows users to share files and messages with nearby devices over their local network without needing an internet connection. In versions up to and including 1.17.0, when a user initiates a "Share via Link" session, the LocalSend application starts a local HTTP server to host the selected files. The client-side logic for this web interface is contained in `app/assets/web/main.js`. Note that at [0], the `handleFilesDisplay` function constructs the HTML for the file list by iterating over the files received from the server. Commit 8f3cec85aa29b2b13fed9b2f8e499e1ac9b0504c contains a patch.

LocalSend is an open-source app to securely share files and messages with nearby devices over local networks without needing an internet connection. In versions 1.16.1 and below, a critical Man-in-the-Middle (MitM) vulnerability in the software's discovery protocol allows an unauthenticated attacker on the same local network to impersonate legitimate devices, silently intercepting, reading, and modifying any file transfer. This can be used to steal sensitive data or inject malware, like ransomware, into files shared between trusted users. The attack is hardly detectable and easy to implement, posing a severe and immediate security risk. This issue was fixed in version 1.17.0.

LocalSend is a free, open-source app that allows users to securely share files and messages with nearby devices over their local network without needing an internet connection. Prior to version 1.17.0, due to the missing sanitization of the path in the `POST /api/localsend/v2/prepare-upload` and the `POST /api/localsend/v2/upload` endpoint, a malicious file transfer request can write files to the arbitrary location on the system, resulting in the remote command execution. A malicious file transfer request sent by nearby devices can write files into an arbitrary directory. This usually allows command execution via the startup folder on Windows or Bash-related files on Linux. If the user enables the `Quick Save` feature, it will silently write files without explicit user interaction. Version 1.17.0 fixes this issue.