| Package | Affected versions | Patched versions |
|---|---|---|
| lightrag-hku | < 1.5.5 | 1.5.5 |
The LightRAG API server passes raw Python exception messages directly into HTTP error responses across 30+ error handlers in every router. When combined with the default unauthenticated configuration (see companion report on CWE-306), any network-reachable client can trigger exceptions whose raw text discloses internal infrastructure — server filesystem paths, database host/port/user, LLM provider error details, and Python library internals. No global exception handler sanitizes error messages before they reach the client.
Throughout the API route handlers, exceptions are caught and their string
representation is returned verbatim via detail=str(e) / detail=str(exc)
(and f-string variants such as detail=f"...: {str(e)}"). This occurs in every
router file. Location breakdown on the current main branch:
HTTP 500 — raw exception passthrough (except Exception as e):
document_routes.py — 13graph_routes.py — 12 (mix of detail=f"...{str(e)}" and detail=error_msg)query_routes.py — 3ollama_api.py — 2lightrag_server.py — 1 (health endpoint)HTTP 422 — raw exception passthrough (except ValueError as exc):
document_routes.py — 2 (chunking-config validation)Total: ~33 raw-exception-to-HTTP-response locations. The only pre-existing
custom exception handler in lightrag_server.py is specific to
RequestValidationError for /query/data; it does not cover the generic
Exception handlers in route code.
Example pattern (document_routes.py, upload handler):
except Exception as e:
logger.error(f"Error /documents/upload: {file.filename}: {str(e)}")
raise HTTPException(status_code=500, detail=str(e))
Categories of sensitive information that can leak through these responses:
Server filesystem paths. File-I/O errors from the default JSON storage
backend expose the server's directory layout
(e.g. [Errno 13] Permission denied: '/app/data/rag_storage/default/kv_store_full_docs.json'),
aiding path-traversal or targeted attacks. (Verified — see PoC Step 1.)
Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site freeDatabase host / port / user / database name. Connection errors from the
PostgreSQL, MongoDB, Redis, or Neo4j backends surface the target the driver
was trying to reach — e.g. asyncpg raises
password authentication failed for user "lightrag" (username) or a socket
error naming the unreachable host and port.
Note on credentials: the PostgreSQL backend uses asyncpg, which is
built from keyword parameters and does not echo the password in its
exception strings — so a raw asyncpg error leaks host/port/user/db, not the
password. URI-configured backends behave differently: the MongoDB backend is
built with AsyncMongoClient(MONGO_URI, ...), and a malformed-URI /
configuration error from pymongo can surface the connection string itself,
which may embed credentials (mongodb://user:password@host:port/). The leak
surface is therefore backend- and error-type-dependent.
LLM provider error details. Errors from OpenAI / Gemini / Bedrock and other providers may include model names, organization ids, or partial API error context that reveal the deployment.
Python library internals. Unexpected exceptions expose class names, library-internal messages, and stack fragments that fingerprint the server stack and version.
Configuration details. Errors during configuration/parsing may reveal storage backend types and other configuration values.
The risk is amplified by the default unauthenticated configuration (CWE-306, companion report), which lets any network client trigger and read these errors without credentials.
Tested on a clean checkout with the [api] extras installed and the server run
via lightrag-server.
With the default storage backend, a file-permission error is returned verbatim:
# Make a storage file unreadable to force an I/O error.
chmod 000 ./rag_storage/default/kv_store_full_docs.json
curl -s http://localhost:9621/documents | python3 -m json.tool
Vulnerable response — the full server-side path is disclosed:
{
"detail": "[Errno 13] Permission denied: '/app/data/rag_storage/default/kv_store_full_docs.json'"
}
Configure a PostgreSQL KV backend pointed at an unreachable / misconfigured host:
LIGHTRAG_KV_STORAGE=PGKVStorage
POSTGRES_HOST=nonexistent-host-12345.example.com
POSTGRES_PORT=5432
POSTGRES_USER=lightrag
POSTGRES_DATABASE=lightrag
A request that touches storage returns the raw connection error, disclosing the host / port / user the server is configured to reach (the asyncpg password is not echoed — see the credentials note above):
{
"detail": "[Errno -2] Name or service not known"
}
For a URI-configured backend such as MongoDB (MONGO_URI=mongodb://user:pass@host:port/db),
a malformed-URI / configuration error can instead surface the connection string
itself, including any embedded credentials.
Error-message information exposure. A client able to reach the LightRAG server can extract:
When combined with the default unauthenticated configuration, any
network client can trigger and read these responses without authentication,
which is why this is scored PR:N.
Replace every detail=str(e) / detail=str(exc) pattern with a generic
client message. Log the full exception server-side (message + traceback) and
return only a generic message plus a correlation id:
except Exception as e:
logger.error(f"Error /documents/upload: {file.filename}: {e!r}")
raise HTTPException(status_code=500, detail="Internal server error")
Register a last-resort global handler as defense-in-depth so any exception that escapes a route is sanitized identically:
@app.exception_handler(Exception)
async def unhandled_exception_handler(request, exc):
logger.error(f"Unhandled exception: {exc!r}", exc_info=True)
return JSONResponse(status_code=500, content={"detail": "Internal server error"})
Preserve genuine client-input validation feedback. The two HTTP 422 chunking-config validators emit controlled, non-sensitive messages; keep them as 422 feedback rather than genericizing to 500 — but wrap the raw exception so it is never a bare passthrough.
Fix status: implemented in HKUDS/LightRAG#3422 — a shared
internal_server_error() helper routes all 500 handlers through a generic body
carrying a correlation id (full detail logged server-side), a global
@app.exception_handler(Exception) is registered in create_app, and the two
422 validators are wrapped.