CVE-2026-42334

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

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.

CVE-2026-42334 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (6.13.9, 7.8.9, 8.22.1, 9.1.6); upgrading removes the vulnerable code path.

Kodem intelligence

Patches have been released for all supported Mongoose release lines:

• ^6.13.9
• ^7.8.9
• ^8.22.1
• ^9.1.6

1. What is CVE-2026-42334? CVE-2026-42334 is a high-severity security vulnerability in mongoose (npm), affecting versions < 6.13.9. It is fixed in 6.13.9, 7.8.9, 8.22.1, 9.1.6.
2. How severe is CVE-2026-42334? CVE-2026-42334 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of mongoose are affected by CVE-2026-42334? mongoose (npm) versions < 6.13.9 is affected.
4. Is there a fix for CVE-2026-42334? Yes. CVE-2026-42334 is fixed in 6.13.9, 7.8.9, 8.22.1, 9.1.6. Upgrade to this version or later.
5. Is CVE-2026-42334 exploitable, and should I be worried? Whether CVE-2026-42334 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42334 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42334?
   • Upgrade mongoose to 6.13.9 or later
   • Upgrade mongoose to 7.8.9 or later
   • Upgrade mongoose to 8.22.1 or later
   • Upgrade mongoose to 9.1.6 or later