{"id":"CVE-2026-48774","summary":"ProxySQL MCP run_sql_readonly executes side-effecting MySQL multi-statements despite read-only contract","details":"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.","aliases":["GHSA-7wh6-2vcc-gcm4"],"modified":"2026-07-08T08:07:13.939964990Z","published":"2026-06-19T19:34:39.971Z","database_specific":{"cwe_ids":["CWE-20"],"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48774.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48774.json"},{"type":"ADVISORY","url":"https://github.com/sysown/proxysql/security/advisories/GHSA-7wh6-2vcc-gcm4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48774"},{"type":"FIX","url":"https://github.com/sysown/proxysql/commit/e32b7fd50c7c234ea628e392e621e09a2a919e08"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sysown/proxysql","events":[{"introduced":"3803f11077f21510b2b43ea7168abf91b54b739e"},{"fixed":"7ddb3dc015d1440e8a0fb0bbafa2df9aaaa2669d"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"3.0.6"},{"fixed":"3.0.9"}]}}],"versions":["v4.0.8","v3.1.8","v3.0.8","3.0.9","3.0.8","v4.0.7","v3.1.7","v3.0.7","v4.0.6","v3.1.6","v3.0.6"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48774.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}