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.
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.