fix(security): do not treat COMMENT/CALL table names as mutations - #64
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Bare \bCOMMENT\b / \bCALL\b scans rejected SELECT * FROM comment. Match statement verbs only (mutating CTEs, WITH … DML, FOR UPDATE). Co-authored-by: Venkat SF <venkatesh.sakamuri@stayflexi.com>
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Summary
Yes, this is a real bug and it should be fixed before anyone hits it on a
commenttable.McpSqlGuardService.containsForbiddenKeyword(and the matching MCP JS shim) scanned the whole statement with\bCOMMENT\b/\bCALL\b. That is an identifier match, not a statement-verb match, so these were rejected as "potentially mutating":SELECT * FROM commentSELECT * FROM callJOIN comment ON comment.id = …SELECT COALESCE(comment, '')SELECT REPLACE(name, 'a', 'b')(REPLACEis also on the forbidden list)This guard sits on dashboard artifact queries (
POST /api/dashboards/queryand the public share query path) as well as/api/mcp/query-readonly. A generated dashboard against acommenttable would fail at the gate.Fix
Stop scanning bare words. Detect mutating statements only:
WITH x AS (DELETE FROM t RETURNING …) SELECT …WITH x AS (SELECT …) DELETE FROM t …SELECT … FOR UPDATEEXPLAIN DELETE …(whileEXPLAIN SELECT * FROM commentstays allowed)Top-level
DELETE/CALL/COMMENT ONwere already rejected by the first-keyword allowlist and still are.Java and JS stay in lockstep.
Test plan
./mvnw test -Dtest=McpSqlGuardServiceTest— 12 tests, 0 failures (FROM comment/FROM callallowed; mutating CTEs andWITH … DELETEstill blocked)node --test mcp/deepsql-phase1-lib.test.js— 78 tests, 0 failures