Meshtastic allows Command Injection in GitHub Action

Meshtastic is an open source mesh networking solution. The main_matrix.yml GitHub Action is triggered by the pull_request_target event, which has extensive permissions, and can be initiated by an attacker who forked the repository and created a pull request. In the shell code execution part, user-controlled input is interpolated unsafely into the code. If this were to be exploited, attackers could inject unauthorized code into the repository. This vulnerability is fixed in 2.6.6.