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 runsqlreadonly 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 CLIENTMULTISTATEMENTS. 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 runsqlreadonly 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-queryendpointauth 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.

ProxySQL is a proxy for MySQL and its forks, as well as PostgreSQL. In versions 2.0.0 through 3.0.8, the ProxySQL MySQL frontend accepts the PROXY UNKNOWN <addr> <addr> <port> <port>\r\n PP1 frame as a well-formed PROXY protocol header. The HAProxy PROXY protocol v1 specification says that when the protocol token is UNKNOWN, the receiver MUST ignore any address fields that follow it, because the proxy has declared it cannot determine the client identity. ProxySQL parses those address fields anyway via sscanf and writes the spoofed source address into the session's addr.addr field. From there it flows directly into the query-rule matcher, where the clientaddr predicate decides routing and ACL. When mysql-proxyprotocolnetworks = '' (the default), any TCP peer can send a PP1 frame and choose any source IP claim. With that, any mysqlqueryrules row pinned to a clientaddr value is forgeable: the attacker writes the address they want to match into the PP1 line, and ProxySQL routes their query as if it came from that address. In practice this is a routing and ACL bypass. Real deployments use clientaddr for read-write splitting (internal apps go to the primary, public traffic to read replicas), per-app schema pinning, and query-filter rules (DDL allowed only from admin CIDR, public queries blocked from dangerous patterns). An attacker that can reach the frontend port can forge their way into any of those routes. Version 3.0.9 patches this issue.

ProxySQL is a proxy for MySQL and its forks, as well as PostgreSQL. Versions 2.0.18 through 3.0.8 have a pre-authentication heap memory corruption vulnerability in the MySQL and PostgreSQL protocol first-read paths. A remote unauthenticated client can declare an oversized first packet length, and ProxySQL passes that attacker-controlled length directly to recv() while writing into a fixed 32 KB input queue. Version 3.0.9 patches the issue.