CVE-2026-1850
📋 TL;DR
This vulnerability allows attackers to crash MongoDB servers by sending complex queries that trigger excessive memory usage in the query planner. All MongoDB deployments using affected versions are vulnerable to denial-of-service attacks. The vulnerability requires query execution privileges to exploit.
💻 Affected Systems
- MongoDB
📦 What is this software?
Mongodb by Mongodb
Mongodb by Mongodb
⚠️ Risk & Real-World Impact
Worst Case
Complete MongoDB service outage due to out-of-memory crashes, leading to application downtime and data unavailability.
Likely Case
Intermittent service disruptions and performance degradation as memory exhaustion causes query failures and restarts.
If Mitigated
Minimal impact with proper query validation, memory limits, and monitoring in place to detect abnormal query patterns.
🎯 Exploit Status
Requires ability to execute complex queries against MongoDB; authenticated access needed but no special privileges beyond query execution.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check MongoDB security advisory for specific fixed versions
Vendor Advisory: https://jira.mongodb.org/browse/SERVER-114126
Restart Required: Yes
Instructions:
1. Check MongoDB security advisory for affected versions. 2. Upgrade to patched version. 3. Restart MongoDB service. 4. Verify fix with test queries.
🔧 Temporary Workarounds
Implement Query Complexity Limits
allRestrict maximum query complexity and execution time to prevent memory exhaustion
db.adminCommand({setParameter: 1, maxTimeMS: 10000})
Use MongoDB's $maxTimeMS operator in queries
Memory Usage Monitoring
allMonitor MongoDB memory usage and implement alerts for abnormal patterns
mongostat --discover
Check MongoDB metrics for memory spikes
🧯 If You Can't Patch
- Implement strict query validation and sanitization to reject overly complex queries
- Deploy MongoDB behind application layer with query filtering and rate limiting
🔍 How to Verify
Check if Vulnerable:
Check MongoDB version against affected versions in security advisory; monitor for query planner memory spikesCheck Version:
mongod --versionVerify Fix Applied:
After patching, test with complex queries and monitor memory usage; verify no crashes occur📡 Detection & Monitoring
Log Indicators:
- Out of memory errors in MongoDB logs
- Query planner memory allocation failures
- MongoDB process crashes/restarts
Network Indicators:
- Sudden increase in query complexity from single sources
- Repeated complex query patterns
SIEM Query:
source="mongodb.log" AND ("out of memory" OR "OOM" OR "query planner" AND "memory")