CVE-2025-3083: MongoDB DOS Vulnerability

CVE-2025-3083 Overview

CVE-2025-3083 is a denial of service vulnerability in MongoDB that allows attackers to crash the mongos query router by sending specifically crafted wire protocol messages. The vulnerability affects the command validation process and can be triggered without requiring an authenticated connection, making it particularly dangerous for internet-exposed MongoDB deployments.

Critical Impact

Unauthenticated attackers can cause mongos instances to crash, potentially disrupting database operations and application availability across sharded MongoDB clusters.

Affected Products

• MongoDB v5.0 versions prior to 5.0.31
• MongoDB v6.0 versions prior to 6.0.20
• MongoDB v7.0 versions prior to 7.0.16

Discovery Timeline

• April 1, 2025 - CVE-2025-3083 published to NVD
• September 22, 2025 - Last updated in NVD database

Technical Details for CVE-2025-3083

Vulnerability Analysis

This vulnerability (CWE-248: Uncaught Exception) exists in the mongos component of MongoDB, which serves as the query router for sharded cluster configurations. When mongos receives a specifically crafted wire protocol message, the command validation logic fails to properly handle malformed input, resulting in an uncaught exception that causes the process to terminate.

The attack can be executed remotely over the network without requiring authentication credentials. This means any attacker with network access to a mongos instance can potentially crash it, causing immediate service disruption. In sharded MongoDB deployments, mongos instances are critical components that route client queries to the appropriate shards, making their availability essential for cluster operations.

Root Cause

The root cause is classified as CWE-248 (Uncaught Exception). The mongos command validation routine does not properly handle certain edge cases in MongoDB wire protocol messages. When these malformed messages are processed, an unhandled exception is thrown that propagates up the call stack without being caught, leading to process termination. This represents an input validation failure where the parser accepts malformed data that subsequently causes the validation logic to fail catastrophically.

Attack Vector

The vulnerability is exploitable over the network without authentication. An attacker can establish a connection to a mongos instance on the default MongoDB port (27017) or any configured port and send malicious wire protocol messages. The attack does not require valid credentials or any prior authentication, significantly lowering the barrier to exploitation.

The MongoDB wire protocol is a binary protocol used for all client-server communication. By crafting specific byte sequences that pass initial protocol parsing but trigger exceptions during command validation, an attacker can reliably crash the mongos process. The attack surface includes any mongos instance accessible over the network, making proper network segmentation and firewall rules critical for mitigation.

Detection Methods for CVE-2025-3083

Indicators of Compromise

• Unexpected mongos process crashes or restarts in cluster monitoring
• Connection attempts from unknown or suspicious IP addresses to mongos ports
• Abnormal wire protocol messages in MongoDB network traffic captures
• Repeated crash logs indicating uncaught exceptions in command validation

Detection Strategies

• Monitor mongos process stability and alert on unexpected terminations
• Implement network intrusion detection rules for malformed MongoDB wire protocol traffic
• Enable verbose logging on mongos instances to capture connection and command details
• Deploy packet inspection at network boundaries to identify suspicious MongoDB traffic patterns

Monitoring Recommendations

• Configure automated alerts for mongos process failures in your monitoring infrastructure
• Set up connection tracking to identify unusual connection patterns to mongos instances
• Monitor for rapid reconnection attempts that may indicate exploitation attempts
• Review MongoDB audit logs for unusual command patterns preceding crashes

How to Mitigate CVE-2025-3083

Immediate Actions Required

• Upgrade MongoDB v5.0 installations to version 5.0.31 or later
• Upgrade MongoDB v6.0 installations to version 6.0.20 or later
• Upgrade MongoDB v7.0 installations to version 7.0.16 or later
• Restrict network access to mongos instances using firewall rules

Patch Information

MongoDB has released patches addressing this vulnerability. The fix is included in MongoDB v5.0.31, v6.0.20, and v7.0.16. Detailed information about the fix can be found in the MongoDB Issue SERVER-103152. Organizations should prioritize upgrading their MongoDB installations to these patched versions immediately.

Workarounds

• Implement strict firewall rules to limit mongos access to trusted client IP addresses only
• Deploy network segmentation to isolate MongoDB infrastructure from untrusted networks
• Enable authentication and require TLS/SSL for all MongoDB connections
• Consider placing mongos instances behind a load balancer with rate limiting capabilities

# Configuration example - Restrict mongos network access with iptables
# Allow MongoDB traffic only from trusted application servers
iptables -A INPUT -p tcp --dport 27017 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 27017 -j DROP

# Enable MongoDB authentication in mongos configuration
# mongos.conf
# security:
#   keyFile: /path/to/keyfile
# net:
#   ssl:
#     mode: requireSSL
#     PEMKeyFile: /path/to/mongodb.pem