T09 · Insecure Skill Coding Practices
Error
- Location
scripts/notion_diary_sync.py:459- Finding
Arbitrary Local File Disclosure Through Unrestricted Image Upload
- Content
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Vulnerability Details
File Location:
scripts/notion_diary_sync.py, lines 236–257 and 459–466
Vulnerability Type: Unrestricted local file read and network upload
Risk Level: HighVulnerable Code
python def upload_small_file(self, path: pathlib.Path) -> str: if not path.exists(): raise NotionSyncError(f"Image file not found: {path}") size = path.stat().st_size if size > MAX_IMAGE_BYTES: raise NotionSyncError( f"Image file is larger than 20 MB and cannot use single-part upload: {path}" ) mime = mimetypes.guess_type(path.name)[0] or "application/octet-stream" create_payload = { "mode": "single_part", "filename": path.name, "content_type": mime, } created = self.request("POST", "/file_uploads", payload=create_payload) file_upload_id = created["id"] boundary = f"----notiondiary{uuid.uuid4().hex}" file_bytes = path.read_bytes()python def resolve_image_reference( client: NotionClient, image_ref: str, strict_images: bool, ) -> ResolvedImage: try: if re.match(r"^https?://", image_ref): parsed = urllib.parse.urlparse(image_ref) name = pathlib.Path(parsed.path).name or "image" return ResolvedImage(source=image_ref, name=name, external_url=image_ref) path = pathlib.Path(image_ref).expanduser().resolve() upload_id = client.upload_small_file(path) return ResolvedImage(source=str(path), name=path.name, file_upload_id=upload_id)Technical Analysis
The
--imageargument is treated as an arbitrary local filesystem path. The implementation expands and resolves that path, then reads the referenced file usingpath.read_bytes()and transmits its contents to the Notion file-upload API.The validation is insufficient for the declared photo-synchronization feature:
- It ch ...[truncated 2907 chars]
- Remediation
View remediation
Remediation Suggestions
-
Restrict upload roots
- Accept local files only from host-managed attachment directories.
- Resolve both the candidate path and approved roots, then verify that the candidate remains beneath an approved root.
- Reject paths outside those directories.
-
Reject unsafe filesystem objects
- Require
path.is_file(). - Reject symbolic links before opening the target.
- Open files using safeguards that prevent symlink races where supported.
- Revalidate the opened file descriptor before reading.
- Require
-
Verify actual image content
- Allow only explicitly supported image formats.
- Validate magic bytes rather than relying on filename extensions or
mimetypes.guess_type(). - Decode the file with a trusted image parser and reject content that cannot be decoded as an image.
- Derive the upload MIME type from verified content.
-
Require explicit authorization
- Ensure every local image originates from a user-provided attachment or an explicitly approved path.
- Require confirmation before accessing paths outside the host’s attachment directory.
- Do not allow diary text or retrieved conversation content to introduce local file paths automatically.
-
Minimize path disclosure
- Do not place absolute local paths or detailed exception messages in Notion fallback paragraphs.
- Replace them with a generic message such as
Image upload failed. - Keep detailed diagnostics local and redact home-directory and credential-related paths.
-
Add security tests
- Verify rejection of files such as SSH keys, environment files, and arbitrary text documents.
- Test path traversal, home-directory expansion, symbolic links, misleading image extensions, malformed images, and files outside approved roots.
- Confirm that valid user attachments continue to upload successfully.
-