MongoDB Under Siege: Critical Memory Leak Exposes Secrets via MongoBleed
- DTG Threat Management Team
- 1 day ago
- 5 min read
CVE-2025-14847 "MongoBleed” MongoDB Unauthenticated Memory Disclosure Vulnerability
Classification: Threat Advisory
Threat Level: High/Advisory
Date Issued: 29 December 2025
Distribution: To: Security Operations Centers (SOC), Database Administrators (DBA), System Owners
Executive Summary
CVE-2025-14847, publicly disclosed and colloquially named "MongoBleed," is a critical, unauthenticated memory disclosure vulnerability affecting MongoDB Server across multiple versions. The vulnerability permits remote, unauthenticated attackers to read uninitialized heap memory directly from the database service when zlib compression is enabled. Threat actors require only network access to exploit this flaw; no authentication credentials, user interaction, or special privileges are necessary. Exploitation is active in the wild, with approximately 87,000 internet-exposed MongoDB instances at risk globally.
The Vulnerability: Zlib Decompression Mishandling Enables Memory Disclosure
MongoBleed arises from improper handling of length fields in MongoDB's zlib-based network message decompression logic (CWE-130). When a client sends a compressed message, the server allocates a buffer based on the declared uncompressed size. In vulnerable versions, the server returns the size of the allocated buffer rather than the actual decompressed data length, causing uninitialized heap memory to be leaked in responses. Critically, this occurs before authentication, allowing attackers to exploit the flaw without valid credentials.
Technical Summary
Attribute | Detail |
CVE ID | CVE-2025-14847 |
Nickname | MongoBleed |
Attack Vector | Network (unauthenticated, pre-authentication) |
CVSS v3.1 score | 7.5 (High) |
CVSS v4.0 score | 8.7 (High) |
Attack Complexity | Low |
Root Cause | Zlib compression handler returns allocated buffer length instead of actual decompressed length; causes uninitialized heap memory over-read |
Exploit Availability | Public PoC released 26 December 2025 (GitHub) |
Exploitation Status | Actively exploited in the wild (confirmed 28–29 December 2025) |
Technical Details
Root Cause: Logic error in message_compressor_zlib.cpp-allocated buffer size returned instead of decompressed length.
Attack Vector: Remote, unauthenticated; requires only network access to MongoDB's default port (27017) with zlib compression enabled.
Impact: High confidentiality loss; attackers can extract credentials, API/cloud keys, session tokens, PII, internal logs, and more.
Affected Software and Version
MongoBleed impacts a broad range of MongoDB Server versions:
8.2.x – Affected through 8.2.2; patched in 8.2.3
8.0.x – Affected through 8.0.16; patched in 8.0.17
7.0.x – Affected through 7.0.27; patched in 7.0.28
6.0.x – Affected through 6.0.26; patched in 6.0.27
5.0.x – Affected through 5.0.31; patched in 5.0.32
4.4.x – Affected through 4.4.29; patched in 4.4.30
4.2.x, 4.0.x, 3.6.x – All versions affected; no patches available (end-of-life)
Threat Intelligence
Threat Actors: No specific Advanced Persistent Threat (APT) group attribution at this time. However, given the vulnerability's ease of exploitation, unauthenticated attack vector, and global prevalence of MongoDB in cloud/SaaS/enterprise environments, both opportunistic cybercriminals and state-sponsored groups are expected to leverage this flaw for initial access, reconnaissance, and credential theft.
Victimology & Targeting: No sector- or country-specific targeting reported. All organizations operating MongoDB instances with internet exposure are at risk. Financial services, healthcare, SaaS platforms, and technology companies are particularly vulnerable due to their reliance on MongoDB for sensitive data storage.
MITRE ATT&CK Alignment: T1046 (Network Service Scanning), T1005 (Data from Local System), T1210 (Exploitation of Remote Services), T1005 (Credentials from Local System), T1056 (Credential Dumping).
Exploitation Indicators & IOCs
Network Indicators:
Unusual inbound traffic to MongoDB port 27017 (or custom ports) from untrusted IP addresses
Malformed zlib-compressed payloads in network traffic
High-velocity connection bursts (50,000–100,000+ connections per minute)
Connections without standard MongoDB client metadata (event ID 51800 in logs)
Log Indicators (MongoDB):
Connection (22943) and disconnection (22944) events with missing client metadata
Inbound unauthenticated connection attempts
Error logs from decompression handlers or zlib processing
Anomalous connection patterns from single source IP address
Detection Rule Signature (aggregated by source IP):
≥100 total connections in short timeframe
<10% presence of client metadata in connections
Connection rate ≥500 connections per minute
Threat Landscape and Observed Exploitation
MongoBleed is being actively exploited in the wild. Public proof-of-concept (PoC) exploit code was released on December 26, 2025, and mass scanning began immediately thereafter. Security researchers and platforms (Wiz, Censys) report:
87,000+ vulnerable internet-facing MongoDB instances worldwide.
42% of cloud environments host at least one vulnerable instance.
Attackers can extract secrets without authentication, and leaked credentials may enable further compromise, including lateral movement and privilege escalation.
Detection and Forensics
Exploitation leaves a forensic footprint: high-velocity connection bursts (up to 100,000+/min) with zero client metadata events.
Defensive hunting: Look for source IPs with thousands of connections but missing metadata in MongoDB logs.
Business Impact
Remote Memory Disclosure and Credential Theft:
Attackers can continuously scrape server memory for sensitive business data, including plaintext passwords, cloud keys, and session tokens.
Bypass of Authentication and Security Controls:
Leaked secrets may enable attackers to bypass authentication, escalate privileges, and access additional systems.
High-Value Targets:
Organizations relying on MongoDB for critical applications (finance, healthcare, government, technology) are at significant risk, especially if instances are internet-exposed or misconfigured.
Confidentiality: Sensitive data at risk includes:
Database credentials and access tokens
Session tokens and API keys
Personally Identifiable Information (PII)
Encryption keys and cryptographic material
Internal application secrets and configuration data
Integrity: No direct impact; vulnerability is read-only disclosure.
Availability: No impact; vulnerability does not affect MongoDB availability.
Downstream Risk: Compromised credentials and tokens can enable further lateral movement, privilege escalation, data theft, and full system compromise.
Mitigation & Response Actions
Immediate (Day 1)
Prioritize patching: Upgrade MongoDB to patched versions (8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, 4.4.30 or newer).
Disable zlib compression (temporary): If patching cannot be completed immediately, disable zlib compression and use alternative compressors (snappy or zstd) via networkMessageCompressors configuration.
Restrict network access: Immediately block all unauthenticated inbound connections to MongoDB ports using firewall rules, security groups, or Kubernetes NetworkPolicies. MongoDB should not be internet-accessible.
Short-term (Days 2–7)
Forensic analysis: Review MongoDB logs and network traffic for indicators of exploitation (see IOCs section).
Credential rotation: If exploitation is suspected or confirmed, rotate all database passwords, API keys, and session tokens that may have been exposed.
Enhanced monitoring: Enable verbose MongoDB logging and implement detection rules to identify anomalous connection patterns.
Long-term (Ongoing)
Patch management: Establish and maintain a rapid patching cycle for MongoDB and all database services.
Network segmentation: Ensure MongoDB is deployed in private network segments, accessible only to authorized application servers and administrators.
Data security posture: Classify sensitive data stored in MongoDB and implement encryption at rest and in transit.
Incident response planning: Update IR playbooks to include MongoDB memory disclosure scenarios and credential compromise procedures.
DTG Recommendations
Immediate Actions for All Organizations Using MongoDB
Restrict Exposure:
Audit all MongoDB instances for internet exposure.
Restrict network access to trusted IPs only.
Disable zlib compression if patching is not immediately possible.
Apply Patches:
Upgrade to patched versions: 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, 4.4.30.
Monitor MongoDB's official advisory for new releases and guidance.
Monitor for Compromise:
Review MongoDB logs for anomalous connection patterns and missing metadata events.
Use available detection tools to hunt for exploitation.
Incident Response:
If compromise is suspected, isolate affected systems and rotate all credentials.
Conduct forensic analysis using log-based detection and memory analysis tools.
Network Segmentation and Hardening:
Deploy MongoDB behind firewalls and enforce strict network segmentation.
Implement robust access controls and intrusion detection/prevention systems.
DTG’s Incident Response and Threat Management teams continue tracking this activity across monitored customer environments. Clients using DTG Wirespeed or Pegasos platforms can request an immediate authentication telemetry review or targeted compromise assessment through standard DTG support channels.
Don’t wait for an attack - reach out to DTG today to ensure your organization is protected.
References
· Varonis
· Aikido
· runZero
· Wiz
· Big Data