* fix: sanitize artifact filenames to prevent path traversal in code output
* test: Mock sanitizeFilename function in process.spec.js to return the original filename
- Added a mock implementation for the `sanitizeFilename` function in the `process.spec.js` test file to return the original filename, ensuring that tests can run without altering the filename during the testing process.
* fix: use path.relative for traversal check, sanitize all filenames, add security logging
- Replace startsWith with path.relative pattern in saveLocalBuffer, consistent
with deleteLocalFile and getLocalFileStream in the same file
- Hoist sanitizeFilename call before the image/non-image branch so both code
paths store the sanitized name in MongoDB
- Log a warning when sanitizeFilename mutates a filename (potential traversal)
- Log a specific warning when saveLocalBuffer throws a traversal error, so
security events are distinguishable from generic network errors in the catch
* test: improve traversal test coverage and remove mock reimplementation
- Remove partial sanitizeFilename reimplementation from process-traversal tests;
use controlled mock returns to verify processCodeOutput wiring instead
- Add test for image branch sanitization
- Use mkdtempSync for test isolation in crud-traversal to avoid parallel worker
collisions
- Add prefix-collision bypass test case (../user10/evil vs user1 directory)
* fix: use path.relative in isValidPath to prevent prefix-collision bypass
Pre-existing startsWith check without path separator had the same class
of prefix-collision vulnerability fixed in saveLocalBuffer.
