PYSEC-2026-2877

Summary

A path traversal vulnerability exists in Pipecat's development runner (src/pipecat/runner/run.py). When the runner is started with the --folder flag, it exposes a GET /files/{filename:path} download endpoint. The filename path parameter is concatenated directly onto args.folder with no containment check. Starlette normalises literal ../ sequences in URLs, but %2F-encoded slashes bypass this normalisation: the path parameter is URL-decoded after routing, so ..%2F..%2Fetc%2Fpasswd resolves to a path two levels above args.folder. An attacker with network access to the runner can read any file the pipecat process has permission to access — including SSH private keys, credentials, and system files — with a single unauthenticated HTTP request.

Confirmed on pipecat-ai 1.1.0 (latest PyPI release) and commit f078df78058ae82a02ce5b23e9e3a99a0917a53d.

Details

The vulnerable code is in src/pipecat/runner/run.py, inside the _configure_server_app() function, lines 249–264:

@app.get("/files/{filename:path}")
async def download_file(filename: str):
    """Handle file downloads."""
    if not args.folder:
        logger.warning(f"Attempting to dowload {filename}, but downloads folder not setup.")
        return

    file_path = Path(args.folder) / filename          # ← no containment check
    if not os.path.exists(file_path):
        raise HTTPException(404)

    media_type, _ = mimetypes.guess_type(file_path)

    return FileResponse(path=file_path, media_type=media_type, filename=filename)

Path(args.folder) / filename joins the caller-supplied filename onto the base directory without calling .resolve() or checking is_relative_to. Python's pathlib does not strip .. segments during join — only .resolve() does. Starlette strips literal ../ from the URL path before the route handler runs, but it decodes percent-encoded characters inside the matched path parameter value. Because %2F decodes to...