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CVE-2025-14847

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By yanxxir
3 min read
CVE-2025-14847

Overview

CVE ID: CVE-2025-14847 Published: December 19, 2025 Severity (CVSS): 8.7 (High) Affected Software/Versions:

  • MongoDB 8.2.0 through 8.2.2
  • MongoDB 8.0.0 through 8.0.16
  • MongoDB 7.0.0 through 7.0.27
  • MongoDB 6.0.0 through 6.0.26
  • MongoDB 5.0.0 through 5.0.31
  • MongoDB 4.4.0 through 4.4.29
  • All versions of MongoDB 4.2.x, 4.0.x, and 3.6.x (these older releases have no official patches available) Vulnerability Type: Unauthenticated Memory Disclosure / Information Leak

Summary MongoBleed (CVE-2025-14847) is a critical MongoDB vulnerability that allows unauthenticated attackers to leak server memory remotely, potentially exposing sensitive data such as credentials and internal application information. It affects multiple MongoDB versions and requires immediate patching on self-hosted systems.

Context

  • MongoDB is a widely used NoSQL database that communicates with clients using a custom binary protocol over TCP.
  • It supports compressed network messages (such as zlib) to improve performance and reduce bandwidth usage.
  • The server fails to properly validate message lengths during decompression. A flaw in MongoDB’s message decompression and length validation logic allows the server to return uninitialized heap memory when handling specially crafted requests.
  • As a result, unauthenticated attackers can remotely leak sensitive data such as credentials and internal application information.

Root Cause

  • The MongoDB server improperly validates compressed message length fields.
  • Uninitialized heap memory is included in server responses.
  • The network message decompression routine trusts attacker-controlled length values without strict bounds checking.

Exploitation (Step-by-Step)

  1. Identify a Vulnerable MongoDB Instance Attackers scan for exposed MongoDB servers accessible over the internet. They look for instances with network compression enabled and running vulnerable versions. Once found, the target’s address and port are configured for exploitation.

  2. Establish a Raw Network Connection A direct connection is made to the MongoDB service using raw network protocols. This allows sending custom protocol messages without using standard database drivers, giving complete control over the communication.

  3. Send a Crafted Compressed Message A specially manipulated message is created with incorrect size information. Normal database data is compressed, but the message header falsely claims a much larger size than the actual content. This mismatch between stated and actual data size creates the conditions for exploitation.

  4. Trigger Memory Disclosure When the server processes the manipulated message, it trusts the incorrect size information due to flawed validation. This causes the server to read beyond its allocated memory buffers, pulling in uninitialized data that wasn’t part of the original message. This leaked memory gets included in the error response sent back.

  5. Extract Sensitive Data The server’s response containing leaked memory is analyzed to extract useful information. The exploit filters through error messages and raw data looking for patterns that resemble credentials, access keys, or application data. Found information is collected, saved for further analysis, and checked for common sensitive patterns like passwords or API keys.

Post Exploitation

This attack can enable attackers to:

  • Recover database credentials, API keys, and authentication tokens from leaked heap memory
  • Hijack active application sessions and impersonate legitimate users
  • Access internal application metadata and configuration secrets
  • Use leaked credentials to move laterally into backend services and cloud infrastructure

Proof Of Concept

  • Establishing direct connection to MongoDB server
  • Sending manipulated compressed message with incorrect size fields
  • Triggering memory read beyond allocated buffers
  • Parsing leaked memory from server responses
  • Extracting credentials and sensitive data from heap

Lessons Learned

  • Don’t rely on client-supplied protocol metadata such as message sizes or compression parameters.
  • All network input must be strictly validated before memory allocation or decompression occurs.
  • Low-level parsing flaws can result in severe data exposure even without authentication bypass.
  • Apply defense-in-depth by limiting network access, enforcing encryption and authentication, and disabling unnecessary features.
  • Continuously monitor for malformed compressed traffic, protocol anomalies, and unexpected server error responses.
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