An issue was discovered in KaiOS 3.0 before 3.1. The /system/bin/tctwebserver binary exposes a local web server that responds to GET and POST requests on port 2929. The server accepts arbitrary Bash commands and executes them as root. Because it is not permission or context restricted and returns proper CORS headers, it's accessible to all websites via the browser. At a bare minimum, this allows an attacker to retrieve a list of the user's installed apps, notifications, and downloads. It also allows an attacker to delete local files and modify system properties including the boolean persist.moz.killswitch property (which would render the device inoperable). This vulnerability is partially mitigated by SELinux which prevents reads, writes, or modifications to files or permissions within protected partitions.

A Denial of Service issue has been discovered in the Gecko component of KaiOS 2.5 10.05 (platform 48.0.a2) on Nokia 8810 4G devices. When a crafted web page is visited with the internal browser, the Gecko process crashes with a segfault. Successful exploitation could lead to the remote code execution on the device.

An issue was discovered in KaiOS 3.0 and 3.1. The binary /system/kaios/api-daemon exposes a local web server on .localhost with subdomains for each installed applications, e.g., myapp.localhost. An attacker can make fetch requests to api-deamon to determine if a given app is installed and read the manifest.webmanifest contents, including the app version.