Impact

The SQL injection exploit is related to replacements. Here is such an example:

In the following query, some parameters are passed through replacements, and some are passed directly through the where option.

User.findAll({
  where: or(
    literal('soundex("firstName") = soundex(:firstName)'),
    { lastName: lastName },
  ),
  replacements: { firstName },
})

This is a very legitimate use case, but this query was vulnerable to SQL injection due to how Sequelize processed the query: Sequelize built a first query using the where option, then passed it over to sequelize.query which parsed the resulting SQL to inject all :replacements.

If the user passed values such as

{
  "firstName": "OR true; DROP TABLE users;",
  "lastName": ":firstName"
}

Sequelize would first generate this query:

SELECT * FROM users WHERE soundex("firstName") = soundex(:firstName) OR "lastName" = ':firstName'

Then would inject replacements in it, which resulted in this:

SELECT * FROM users WHERE soundex("firstName") = soundex('OR true; DROP TABLE users;') OR "lastName" = ''OR true; DROP TABLE users;''

As you can see this resulted in arbitrary user-provided SQL being executed.

Patches

The issue was fixed in Sequelize 6.19.2

Workarounds

Do not use the replacements and the where option in the same query if you are not using Sequelize >= 6.19.2.

References

See this thread for more information: #14519

Snyk: https://security.snyk.io/vuln/SNYK-JS-SEQUELIZE-2932027