GHSA-6jrf-rcjf-245r changedetection.io path traversal using file URI scheme without supplying hostname

• PyPI changedetection.io: < 0.47.6 → fixed in 0.47.6

Summary The validation for the file URI scheme falls short, and results in an attacker being able to read any file on the system. This issue only affects instances with a webdriver enabled, and `ALLOW_FILE_URI` false or not defined. Details The check used for URL protocol, `is_safe_url`, allows `file:` as a URL scheme: https://github.com/dgtlmoon/changedetection.io/blob/e0abf0b50507a8a3d0c1d8522ab23519b3e4cdf4/changedetectionio/model/Watch.py#L11-L13 It later checks if local files are permitted, but one of the preconditions for the check is that the URL starts with `file://`. The issue comes with the fact that the file URI scheme is not required to have double slashes. > A valid file URI must therefore begin with either `file:/path` (no hostname), `file:///path` (empty hostname), or `file://hostname/path`. > — Wikipedia https://github.com/dgtlmoon/changedetection.io/blob/e0abf0b50507a8a3d0c1d8522ab23519b3e4cdf4/changedetectionio/processors/__init__.py#L37-L41 PoC 1. Open up a changedetection.io instance with a webdriver configured 2. Create a new watch: `file:/etc/passwd` or a similar path for your operating system. Enable webdriver mode 3. Wait for it to be checked 4. Open preview 5. Notice contents of the file