CVE-2026-42334 — mongoose
HIGHCVE-2026-42334 is a high-severity (CVSS 7.5) CWE-74 vulnerability in mongoose. A fix is available for mongoose — see the affected versions and patch details below.
Mongoose: Improper Sanitization of $nor in sanitizeFilter May Allow NoSQL Injection
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42334.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-42334 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
mongoosenpmDescription
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 onsanitizeFilterto 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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | mongoose | all versions | 6.13.9npm install mongoose@6.13.9 |
| 📦npm | mongoose | ≥ 7.0.0&&< 7.8.9 | 7.8.9npm install mongoose@7.8.9 |
| 📦npm | mongoose | ≥ 8.0.0&&< 8.22.1 | 8.22.1npm install mongoose@8.22.1 |
| 📦npm | mongoose | ≥ 9.0.0&&< 9.1.6 | 9.1.6npm install mongoose@9.1.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mongoose, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mongoose to 6.13.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42334 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-42334 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-42334. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-42334 in your dependencies?
O3 Security finds CVE-2026-42334 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.