CVE-2026-48774
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk13th percentile — higher than 13% of all known CVEs
Summary
In versions 3.0.0 to 3.0.8, the `run_sql_readonly` tool in ProxySQL violates the read-only contract for MySQL targets, allowing the execution of data-modifying commands. A caller can submit a read-only first statement followed by a second statement that has side effects, such as `RENAME TABLE`.
Risk Assessment
The breach of the read-only contract can lead to unauthorized data modifications in the database, posing a serious risk to data integrity and system security. Users with appropriate privileges may execute dangerous operations on the database.
Recommendation
It is recommended to upgrade to version 3.0.9, which contains a fix. Additionally, consider disabling MCP if not needed and implementing appropriate security rules for MCP queries.
Original NVD description (English source)
ProxySQL is a proxy for MySQL and its forks, as well as PostgreSQL. In versions 3.0.0 through 3.0.8, ProxySQL's GenAI/MCP `run_sql_readonly` tool violates its documented read-only contract for MySQL targets. The tool validates only the full input string with a substring blacklist and first-keyword allowlist, but then executes the entire SQL string on a backend connection created with `CLIENT_MULTI_STATEMENTS`. As a result, a caller can submit a read-only first statement followed by a side-effecting second statement, such as `SELECT 1; RENAME TABLE ...`. The validator accepts the payload because it starts with `SELECT` and because side-effecting MySQL statements such as `RENAME TABLE`, `SET`, `RESET`, `LOCK TABLES`, and `KILL` are not rejected by the blacklist. In a live MCP runtime test, the `/mcp/query` endpoint accepted a `run_sql_readonly` request. The MCP response reported success for the first `SELECT`, and direct backend verification showed that the table had actually been renamed. This violates the endpoint's read-only security contract and lets an MCP caller perform backend writes or administrative SQL, limited by the configured MCP target account's database privileges. Version 3.0.9 contains a fix. Other operator mitigations include: keeping MCP disabled unless required; setting a non-empty `mcp-query_endpoint_auth` token before exposing `/mcp/query`; restricting MCP listener network exposure; configuring MCP backend target credentials as database-level read-only users; and adding temporary MCP query rules to block obvious multi-statement patterns.