check-jsonschema is a CLI and set of pre-commit hooks for jsonschema validation. The default cache strategy uses the basename of a remote schema as the name of the file in the cache, e.g. https://example.org/schema.json will be stored as schema.json. This naming allows for conflicts. If an attacker can get a user to run check-jsonschema against a malicious schema URL, e.g., https://example.evil.org/schema.json, they can insert their own schema into the cache and it will be picked up and used instead of the appropriate schema. Such a cache confusion attack could be used to allow data to pass validation which should have been rejected. This issue has been patched in version 0.30.0. All users are advised to upgrade. A few workarounds exist: 1. Users can use --no-cache to disable caching. 2. Users can use --cache-filename to select filenames for use in the cache, or to ensure that other usages do not overwrite the cached schema. (Note: this flag is being deprecated as part of the remediation effort.) 3. Users can explicitly download the schema before use as a local file, as in curl -LOs https://example.org/schema.json; check-jsonschema --schemafile ./schema.json
The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.