---
title: "GHSA-q8r4-6gpp-5fx2"
description: "QueryGuard ignores MySQL executable comments, bypassing table allow-lists and PII column protection. Affected and fixed versions of qwed-finance."
url: https://qwedai.com/security/advisories/ghsa-q8r4-6gpp-5fx2
---

# GHSA-q8r4-6gpp-5fx2

QueryGuard ignores MySQL executable comments, bypassing table allow-lists and PII column protection

### Impact

`QueryGuard` in `qwed-finance` parses SQL without a dialect, and the parser treats MySQL executable comments (`/*! ... */` and `/*!NNNNN ... */`) as ordinary comments. MySQL and MariaDB execute the contents of these comments. Table references and columns placed inside an executable comment are therefore invisible to the table allow-list and to PII column enforcement, while the database still reads them.

Reproduced on v3.0.0:

| Call | Result |
| --- | --- |
| `QueryGuard().verify_table_access("SELECT a FROM t1 /*!50000 , t2 */", {"t1"})` | **`safe=True`** , tables `['t1']`, no violations (MySQL reads `t2`) |
| `CrossGuard().verify_query_with_pii_protection("SELECT a /*!50000 , ssn */ FROM t1", ["t1"], ["ssn"])` | **`passed=True`** , no violations (MySQL projects `ssn`) |
| `QueryGuard().sanitize_query("SELECT a FROM t1 /*!50000 , t2 */")` | `safe=True`, `sanitized_query` returned unchanged, including the executable comment |

**Who is affected:** applications that execute LLM-generated SQL against MySQL or MariaDB and rely on `QueryGuard` / `CrossGuard` for table allow-listing or PII column protection. Other database engines do not execute these comments.

### Root cause

`query_guard.py` calls `sqlglot.parse_one(sql_query)` with no dialect and drops comments, and `sanitize_query` returns the original input string instead of a re-serialized form of what was analysed. The analysed AST and the executed statement differ.

### Patches

Fixed in **qwed-finance 3.0.1** ([release](https://github.com/QWED-AI/qwed-finance/releases/tag/v3.0.1)). Upgrade with `pip install -U qwed-finance==3.0.1`.

Any query containing a MySQL `/*! ... */` or MariaDB `/*M! ... */` executable comment is now unsafe in `verify_readonly_safety`, and therefore in `verify_table_access`, `verify_column_access`, `sanitize_query` and `CrossGuard.verify_query_with_pii_protection`. `sanitize_query` no longer rewrites such queries. Ordinary comments and optimizer hints (`/*+ ... */`) are unaffected.

### Workarounds

-   Reject any query containing `/*!` before verification when the target is MySQL or MariaDB.
-   Execute the re-serialized AST rather than the original string, and use database-level permissions (a read-only role with access only to permitted tables and columns) as the actual enforcement boundary.

### References

Reproduced on `qwed-finance` 3.0.0 (`bb0cdf3`).