Tina is a headless content management system. Prior to 2.1.2, TinaCMS allows users to create, update, and delete content documents using relative file paths (relativePath, newRelativePath) via GraphQL mutations. Under certain conditions, these paths are combined with the collection path using path.join() without validating that the resolved path remains within the collection root directory. Because path.join() does not prevent directory traversal, paths containing ../ sequences can escape the intended directory boundary. This vulnerability is fixed in 2.1.2.

Affected: npm: @tinacms/graphql

### Description

TinaCMS allows users to create, update, and delete content documents using relative file paths (`relativePath`, `newRelativePath`) via GraphQL mutations. Under certain conditions, these paths are combined with the collection path using `path.join()` without validating that the resolved path remains within the collection root directory.

Because `path.join()` does not prevent directory traversal, paths containing `../` sequences can escape the intended directory boundary.

### Attack Vectors

1. **File Creation**: Create files outside the collection directory ```graphql createDocument( collection: "post" relativePath: "../../config/malicious.md" params: { post: { title: "malicious" } } ) ```

2. **File Move/Rename**: Move existing files outside the collection ```graphql updateDocument( collection: "post" relativePath: "existing.md" params: { relativePath: "../../stolen.md" } ) ```

3. **File Deletion**: Delete files outside the collection ```graphql deleteDocument( collection: "post" relativePath: "../../important-config.md" ) ```

4. **Folder Creation**: Create folders outside the collection ```graphql createFolder( collection: "post" relativePath: "../../malicious-folder" ) ```

## Impact

An authenticated user with document mutation permissions can:

- **Create content files** outside collection boundaries (subject to schema validation) - **Move or rename file…