| summary |
Mongoose's Improper Sanitization of $nor in sanitizeFilter May Allow NoSQL Injection
### Impact
This vulnerability allows bypassing Mongoose’s sanitizeFilter query sanitization mechanism via the `$nor` operator.
When sanitizeFilter is enabled, Mongoose wraps query operators in `$eq` to neutralize them. However, prior to the fix, `$nor` was not included in the set of logical operators that are recursively sanitized. Because `$nor` accepts an array (like `$and` and `$or`), and arrays do not trigger `hasDollarKeys()`, malicious operators such as `$ne`, `$gt`, or `$regex` could be injected inside a `$nor` clause without being sanitized.
This may lead to:
- Authentication bypass
- Unauthorized data access
- Data exfiltration
**Affected users:**
Applications that:
- Explicitly enable sanitizeFilter
- Pass unsanitized user-controlled input directly into query methods (e.g., `Model.findOne(req.body)`) and rely on `sanitizeFilter` to strip out query selectors
Applications that validate input schemas, whitelist fields, or avoid passing raw request bodies into queries are not affected. For example, `Model.findOne({ user: req.body.user, pwd: req.body.pwd })` is not affected.
### Patches
Patches have been released for all supported Mongoose release lines:
- `^6.13.9`
- `^7.8.9`
- `^8.22.1`
- `^9.1.6`
### Workarounds
Delete `$nor` keys, use an additional schema validation library, or write middleware to strip out `$nor` from query filters.
### Resources
sanitizeFilter documentation: https://mongoosejs.com/docs/api/mongoose.html#Mongoose.prototype.sanitizeFilter()
Original blog post on sanitizeFilter: https://thecodebarbarian.com/whats-new-in-mongoose-6-sanitizefilter.html |