Mongoose Query Sanitization Bypass Via $nor Operator (CVE-2026-42334)
A critical vulnerability, CVE-2026-42334, has been identified in Mongoose, the popular MongoDB object modeling tool. The National Vulnerability Database reports that prior to versions 6.13.9, 7.8.9, 8.22.1, and 9.1.6, Mongoose’s sanitizeFilter query sanitization mechanism could be bypassed using the $nor operator. This flaw carries a CVSS score of 7.5 (High).
Normally, when sanitizeFilter is enabled, Mongoose wraps query operators in $eq to neutralize them. However, the $nor operator was not included in the set of logical operators that are recursively sanitized. Because $nor accepts an array, similar to $and and $or, and arrays do not trigger the hasDollarKeys() function, malicious operators like $ne, $gt, or $regex could be injected inside a $nor clause without proper sanitization. This opens a clear path for query injection attacks.
This is a severe logic flaw. Attackers can craft specific queries to bypass intended security controls, potentially leading to unauthorized data access, modification, or denial of service, depending on how the application uses these filters. The fix is available in Mongoose versions 6.13.9, 7.8.9, 8.22.1, and 9.1.6. Defenders need to prioritize these updates.
What This Means For You
- If your application uses Mongoose and relies on `sanitizeFilter` for input validation, you are exposed. This isn't theoretical; it's a bypass of a core security mechanism. Review your Mongoose version immediately. Patch to at least 6.13.9, 7.8.9, 8.22.1, or 9.1.6. Assume that if you haven't patched, an attacker could already be probing for this specific `$nor` injection vector to manipulate your database queries.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-42334 - Mongoose Query Sanitization Bypass via $nor Operator
title: CVE-2026-42334 - Mongoose Query Sanitization Bypass via $nor Operator
id: scw-2026-05-14-ai-1
status: experimental
level: high
description: |
Detects attempts to exploit CVE-2026-42334 by identifying web requests containing the '$nor' operator in conjunction with other unsanitized operators like '$ne', '$gt', or '$regex' within the query string. This indicates a potential bypass of Mongoose's query sanitization.
author: SCW Feed Engine (AI-generated)
date: 2026-05-14
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-42334/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri-query|contains:
- '$nor'
cs-uri-query|contains:
- '$ne'
cs-uri-query|contains:
- '$gt'
cs-uri-query|contains:
- '$regex'
condition: cs-uri-query
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-42334 | Auth Bypass | Mongoose versions prior to 6.13.9, 7.8.9, 8.22.1, and 9.1.6 |
| CVE-2026-42334 | Auth Bypass | Mongoose sanitizeFilter query sanitization bypass |
| CVE-2026-42334 | Auth Bypass | Injection of malicious operators ($ne, $gt, $regex) via $nor operator in Mongoose queries |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 14, 2026 at 21:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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