A critical vulnerability in multiple versions of MongoDB, known as MongoBleed (CVE-2025-14847), is already being actively exploited and poses a real risk to thousands of companies. Currently, over 80,000 servers could be exposed on the Internet without proper protection.
The issue is even more serious because a public exploit already exists, along with technical documentation showing how an attacker can leverage this flaw to remotely extract credentials, secrets, and other sensitive data directly from the memory of an accessible MongoDB server.
Due to its high impact, the vulnerability received a severity score of 8.7, placing it in the critical category. MongoDB has already released an official patch for self-hosted environments, available since December 19. At TecnetOne, we strongly recommend updating as soon as possible to prevent security breaches.
The MongoBleed vulnerability is directly related to how the MongoDB server processes certain compressed network packets using the zlib library, which is used for lossless data compression. The problem doesn’t lie in the compression itself, but in how the server manages memory during the decompression process.
According to researchers at Ox Security, MongoDB returns to the client the amount of memory allocated when processing a network message, instead of strictly limiting it to the actual size of the decompressed data. This behavior opens the door to an unintended leak of sensitive information.
In practice, an attacker can send a malformed message that declares a larger decompression size than the actual data. This forces the server to allocate a memory buffer larger than needed, ultimately exposing memory fragments that may contain confidential data.
The information that can be leaked through this exploit is especially sensitive and may include database credentials, API or cloud service keys, session tokens, personal identifiable information (PII), internal logs, configurations, system paths, and client-related data.
One of the factors that makes MongoBleed particularly dangerous is that the decompression process occurs before authentication. This means an attacker does not need valid credentials to exploit the flaw—it's enough for the MongoDB instance to be exposed.
The public exploit, released as a proof of concept (PoC) under the name MongoBleed by Joe Desimone, a security researcher at Elastic, was specifically designed to extract sensitive information directly from the memory of the affected server.
In this regard, researcher Kevin Beaumont confirmed that the PoC code is fully functional and warned that all it takes is the IP address of an exposed MongoDB instance to begin scanning the memory and locating data such as plaintext passwords, AWS secret keys, and other critical secrets.
At TecnetOne, we recommend treating this vulnerability as a top security priority, applying the available patches, and urgently reviewing any MongoDB instances accessible from the Internet.
MongoBleed exploit leaks secrets (Source: Kevin Beaumont)
Read more: Security Patch and Software Updates
According to data from Censys, a platform specializing in the discovery of exposed services on the Internet, as of December 27, more than 87,000 potentially vulnerable MongoDB instances were identified as accessible from the public web. This volume confirms that MongoBleed is not an isolated risk, but a threat with global reach.
The largest number of exposed servers is concentrated in the United States, with around 20,000 instances, followed by China with approximately 17,000, and Germany with just under 8,000 Internet-visible servers.
MongoDB instances exposed on the public internet (Source: Censys)
The impact of this vulnerability in cloud environments is also significant. According to reports, 42% of the analyzed systems have at least one MongoDB instance running a version vulnerable to CVE-2025-14847.
Researchers note that these instances include both internal resources and publicly exposed databases, and confirm having observed active exploitation of MongoBleed in real-world environments. For this reason, we urge companies to prioritize patching as an urgent security measure.
Although not officially confirmed, some threat actors claim to have used this vulnerability in a recent security breach involving Ubisoft’s Rainbow Six Siege online platform, further underscoring the severity of the current situation.
From a defensive standpoint, applying the patch is only the first step. Cybersecurity specialists agree that organizations must also check for possible indicators of compromise, even after updating, since the vulnerability may have been exploited before it was patched.
One recommended detection method involves analyzing MongoDB logs, focusing on source IP addresses that generate hundreds or thousands of connections without associated metadata events. This anomalous behavior can be a clear sign of exploitation.
However, this approach has limitations. Detection relies on the currently known proof-of-concept exploit, meaning a more sophisticated attacker could alter the behavior of the attack, insert fake metadata, or reduce connection frequency to evade detection and remain unnoticed.
As a complement, specific detection tools have been developed, such as the MongoBleed detector, which analyzes MongoDB logs for signs of CVE-2025-14847 exploitation, helping organizations identify potential compromises more effectively.
MongoDB officially addressed the MongoBleed vulnerability just over ten days ago and was clear in its recommendation: update immediately to a secure version. The patched versions include:
8.2.3
8.0.17
7.0.28
6.0.27
5.0.32
4.4.30
The vendor also confirmed that a wide range of versions is affected, including both legacy editions and recent versions released up until November 2025, including:
MongoDB 8.2.0 to 8.2.3
MongoDB 8.0.0 to 8.0.16
MongoDB 7.0.0 to 7.0.26
MongoDB 6.0.0 to 6.0.26
MongoDB 5.0.0 to 5.0.31
MongoDB 4.4.0 to 4.4.29
All versions of MongoDB Server v4.2
All versions of MongoDB Server v4.0
All versions of MongoDB Server v3.6
For MongoDB Atlas, the fully managed multi-cloud database service, patches were applied automatically, so customers do not need to take any additional action.
MongoDB also made one key point clear: there is no complete workaround for this vulnerability. If immediate updating is not possible, the only recommended temporary measure is to disable zlib compression on the server, following the vendor’s official guidance.
As safer alternatives for lossless data compression, MongoDB recommends using Zstandard (zstd) and Snappy, technologies maintained by Meta and Google, respectively.
At TecnetOne, we emphasize the importance of updating, auditing, and actively monitoring any environment using MongoDB—especially those exposed to the Internet or integrated into critical infrastructure.
Having a Security Operations Center (SOC) like TecnetOne’s allows for real-time detection of abnormal behavior, event correlation, identification of potential exploitation attempts, and rapid incident response—helping to reduce the impact of vulnerabilities like MongoBleed and strengthen your company’s security posture.